Systems, devices, and methods for laser-induced breakdown spectroscopy of fluid samples

Abstract

Systems, devices, and methods for laser-induced breakdown spectroscopy (LIBS) analysis of a fluid sample are disclosed. The system can include a laser source for generating excitation light along an excitation light path, a flow cell enclosing a flow cell chamber and including a sample injector to supply the sample along a flow path within the chamber, an input optical port allowing the excitation light inside the chamber to intersect the flow path and energize the sample to form a plasma, and an output optical port allowing LIBS emission light from the plasma to exit the chamber along an emission light path. The system can also include measurement optics along the light paths, a spectral detection device for detecting the emission light, and a curtain gas channel conveying curtain gas to deflect sample ejections from the plasma away from the light paths and impede the ejections from reaching the measurement optics.

Description

SYSTEMS, DEVICES, AND METHODS FOR LASER-INDUCED BREAKDOWN SPECTROSCOPY OF FLUIDSAMPLESCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under applicable laws to U.S. Provisional Patent Application No. 63 / 615,839 filed on December 29, 2023, the content of which is incorporated herein by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The technical field generally relates to analytical spectroscopy and, more particularly to techniques for laser-induced breakdown spectroscopy (LIBS) of fluid samples in various industrial, commercial, and scientific applications.BACKGROUND

[0003] Laser-induced breakdown spectroscopy (LIBS) is a plasma-based atomic emission analytical technique used for elemental analysis of a wide range of materials. A high-energy laser is utilized to generate a plasma at the surface of a sample. The constituent elements of the sample are energized to an excited state within the plasma. Upon relaxation to a lower-energy state, each constituent element emits electromagnetic radiation at one or more element-specific wavelengths. The emitted light can be detected as a LIBS spectrum, which can be analyzed to derive the elemental composition information about the sample.

[0004] LIBS has been primarily used with solid samples, but it is also applicable to aqueous and other liquid samples, although with additional challenges. Such challenges include liquid splashing, liquid surface ripples and turbulence, and the generation of droplets and aerosols above the liquid surface. Liquid splashing can occur due to laser-sample interactions, and it can degrade measurement accuracy and reproducibility. The presence of droplets or aerosols in the plasma region or in the excitation and emission light paths can adversely affect the plasma emission signals. For example, droplets can scatter or absorb LIBS emission light, leading to signal suppression or enhancement depending on the droplet size, analyte concentration, liquid solvent physical characteristics, or position within the plasma. This can result in distorted spectra and inaccurate elemental quantification. Splashing by droplets or aerosols ejected from the sample due to laser irradiation can contaminate or damage optical components disposed along the excitation and emission light paths. These sample ejections can interfere with LIBS emission light and introduce errors in the analysis of the experimental results. Sample ejections may also result in sample loss, leading to reduced sample volumeand potential changes in analyte concentration, which in turn can affect the LIBS measurement accuracy and precision. Despite advances in the field, challenges remain in the development of LIBS techniques for fluid sample characterization.SUMMARY

[0005] The present disclosure generally relates to techniques, including systems, devices, and methods, for characterization and analysis of fluid samples using LIBS. The disclosed techniques can find use in various industries, notably in mining (such as in direct lithium extraction (DLE) operations), oil and gas, water treatment, pharmaceuticals, and agriculture.

[0006] The disclosed embodiments generally use a flow cell and a curtain gas channel. The flow cell defines a flow cell chamber and includes a sample injection port, an input optical port, and an output optical port. The sample injection port is configured to supply a flow of a fluid sample along a sample flow path within the flow cell chamber. The input optical port is configured to allow excitation laser light from a laser source to enter the flow cell chamber along an excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma. The output optical port is configured to allow LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path terminating on a spectral detection device configured to detect the LIBS emission light. The curtain gas channel is configured to convey a flow of curtain gas therealong to deflect sample ejections emanating from the laser- induced plasma away from the excitation light path and / orthe emission light path. In this manner, the sample ejections are prevented or least inhibited from reaching measurement optics (e.g., lenses, mirrors, and filters) interposed along the excitation / emission light paths between the flow cell and the laser source / spectral detection device. The provision of the curtain gas channel can reduce liquid splashing and associated issues and challenges relatingto measurement inaccuracies, contamination and damage of the measurement optics, and overall performance degradation. These advantages can lead to the measurement optics necessitating less frequent cleaning or maintenance, which can be desirable or required in real-time or continuous LIBS measurements conducted in ongoing processes and operations.

[0007] The embodiments disclosed herein include the following aspects:1. A system for laser-induced breakdown spectroscopy (LIBS) analysis of a fluid sample, the system comprising: a laser source configured to generate excitation laser light along an excitation light path; a flow cell comprising:a flow cell body enclosing a flow cell chamber; a sample injection port configured to supply a flow of the fluid sample along a sample flow path within the flow cell chamber; an input optical port configured to allow the excitation laser light to enter the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma; and an output optical port configured to allow LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path; a spectral detection device configured to detect the LIBS emission light exiting the flow cell chamber; measurement optics disposed along the excitation light path and the emission light path; and a curtain gas channel configured to convey a flow of curtain gas therealong to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path to impede the sample ejections from reaching the measurement optics.2. The system of aspect 1, wherein the laser source is configured to generate the excitation laser light with an excitation wavelength ranging from about 200 nm to about 2000 nm.3. The system of aspect 1 or 2, wherein the measurement optics are positioned outside the flow cell chamber.4. The system of any one of aspects 1 to 3, wherein the measurement optics comprises one or more lenses, and / or one or more mirrors, and / or one or more spectral filters.5. The system of any one of aspects 1 to 4, wherein the sample flow path is substantially perpendicular to the excitation light path and the emission light path.6. The system of any one of the aspects 1 to 5, wherein the sample injection port is configured to supply the fluid sample as a mist.7. The system of any one of aspects 1 to 6, wherein the sample injection port comprises a nozzle.8. The system of any one of aspects 1 to 5, wherein the sample injection port is configured to supply the fluid sample as an open-stream flow.9. The system of any one of aspects 1 to 8, wherein the sample injection port is configured to supply the fluid sample as a laminar flow.10. The system of any one of aspects 1 to 9, wherein the sample injection port is configured to supply the fluid sample to flow substantially along the direction of gravity.11. The system of any one of aspects 1 to 9, wherein the sample injection port is configured to supply the fluid sample to flow substantially transverse to the direction of gravity.12. The system of any one of aspects 1 to 11, wherein the sample injection port comprises a capillary tube.13. The system of any one of aspects 1 to 12, wherein the flow cell body comprises at least one opening formed therethrough that defines the input optical port and the output optical port.14. The system of aspect 13, wherein the at least one opening comprises distinct first and second openings, the first opening corresponding to the input optical port and the second opening corresponding to the output optical port.15. The system of aspect 13, wherein the at least one opening comprises a single opening.16. The system of any one of aspects 13 to 15, wherein the flow cell body comprises a cavity formed therein that defines the curtain gas channel, and wherein the cavity overlaps and extends across the at least one opening.17. The system of any one of aspects 1 to 16, wherein the curtain gas channel comprises a single curtain gas flow path that establishes a gas curtain across both the input optical port and the output optical port.18. The system of any one of aspects 1 to 16, wherein the curtain gas channel comprises distinct first and second curtain gas flow paths, the first curtain gas flow path establishing a first gas curtain across the input optical port and the second curtain gas flow path establishing a second gas curtain across the output optical port.19. The system of any one of aspects 1 to 18, wherein the flow of curtain gas along the curtain gas channel is substantially in a same direction as the flow of the fluid sample along the sample flow path.20. The system of any one of aspects 1 to 18, wherein the flow of curtain gas along the curtain gas channel is substantially in an opposite direction to the flow of the fluid sample along the sample flow path.21. The system of any one of aspects 1 to 20, wherein the flow of curtain gas along the curtain gas channel is substantially along the direction of gravity.22. The system of any one of aspects 1 to 20, wherein the flow of curtain gas along the curtain gas channel is substantially against the direction of gravity.23. The system of any one of aspects 1 to 22, wherein the curtain gas comprises air, nitrogen, or argon.24. The system of any one of aspects 1 to 23, further comprising a curtain gas supply unit configured to supply the curtain gas into the curtain gas channel.25. The system of aspect 24, wherein the curtain gas supply unit is configured to supply the curtain gas into the curtain gas channel in a blow mode.26. The system of aspect 24, wherein the curtain gas supply unit is configured to supply the curtain gas into the curtain gas channel in a suction mode.27. The system of any one of aspects 24 to 26, wherein the curtain gas supply unit comprises an injection nozzle configured to control the flow of the curtain gas injected into the curtain gas channel.28. The system of any one of aspects 1 to 27, wherein the flow cell body comprises a base, a cover, and a sidewall extending along a flow cell axis between the base and the cover.29. The system of aspect 28, wherein the flow cell body has a substantially cylindrical configuration about the flow cell axis.30. The system of aspect 28 or 29, wherein the sample flow path is substantially parallel to the flow cell axis.31. The system of aspect 28 or 29, wherein the sample flow path is tilted relative to the flow cell axis in a tilt direction which, in a plane perpendicular to the flow cell axis, points away from the input optical port and / or the output optical port.32. The system of any one of aspects 28 to 31, wherein the sample injection port extends within the flow cell chamber via an opening formed through the cover and is configured to supply the fluid sample to flow along the sample flow path toward the base.33. The system of any one of aspects 28 to 32, wherein the input optical port and the output optical port are formed through the sidewall.34. The system of any one of aspects 28 to 33, wherein an angular separation between the input optical port and the output optical port in a plane perpendicular to the flow cell axis ranges from about 1° to about 20°.35. The system of any one of aspects 28 to 34, wherein the curtain gas channel extends within the sidewall between a curtain gas inlet and a curtain gas outlet, the curtain gas inlet is arranged at one of the base and the cover, and the curtain gas outlet is arranged at the other one of the base and the cover.36. The system of aspect 35, wherein the curtain gas channel has an annular-sector-shaped cross-section in a plane perpendicular to the flow of curtain gas.37. The system of any one of aspects 1 to 36, further comprising a sample collector configured to collect the fluid sample after interaction of the fluid sample with the excitation laser light.38. The system of aspect 37, further comprising a sample discharge port configured to remove the fluid sample from the sample collector.39. The system of any one of aspects 1 to 38, further comprising an ejection collector configured to collect the sample ejections conveyed along and discharged from the curtain gas channel.40. The system of any one of aspects 1 to 39, wherein the spectral detection unit comprises a spectrometer and an optical detector.41. The system of any one of aspects 1 to 40, further comprising a computer device operatively coupled to the spectral detection device, wherein the computer device comprises a processor and a non-transitory computer readable storage medium having stored thereon computer readable instructions that, when executed by the processor, cause the processor to analyze the LIBS emission light detected by the spectral detection device and derive therefrom analyte information about a presence or absence of one or more constituent elements in the fluid sample.42. The system of aspect 41, wherein the analyte information further comprises a concentration of the one or more constituent elements in the fluid sample.43. The system of aspect 41 or 42, wherein the one or more constituent elements in the fluid sample comprise Li, or Na, or Ca, or Mg, or Al, or K, or S, or B, or P, or Si, or Pb, or As, or Hg, or Cd, or any combination thereof.44. The system of any one of aspects 1 to 43, wherein the sample fluid is an aqueous sample.45. The system of any one of aspects 1 to 44, wherein the sample fluid is a lithium-containing brine.46. The system of any one of aspects 1 to 44, wherein the sample fluid is a plant nutrient solution.47. The system of any one of aspects 1 to 46, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid stream flowing within a conduit.48. The system of any one of aspects 1 to 46, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid contained in a fluid reservoir.49. The system of any one of aspects 1 to 48, wherein the the sample injection port is configured with a filtration apparatus.50. The system of any one of aspects 1 to 49, wherein the curtain gas channel is configured to convey the flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.51. A flow cell device for use in laser-induced breakdown spectroscopy (LIBS) analysis of a fluid sample, the flow cell device comprising: a flow cell comprising: a flow cell body enclosing a flow cell chamber; a sample injection port configured to supply a flow of the fluid sample along a sample flow path within the flow cell chamber; an input optical port configured to allow excitation laser light from a laser source to enter the flow cell chamber along an excitation light path intersecting the sample flow path and energize the fluid sample to form a laser-induced plasma; and an output optical port configured to allow LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path leading to a spectral detection device; and a curtain gas channel configured to convey a flow of curtain gas therealong to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path.52. The flow cell device of aspect 51, wherein the sample injection port is configured to supply the fluid sample as an open-stream flow.53. The flow cell device of aspect 51 or 52, wherein the sample injection port is configured to supply the fluid sample as a laminar flow.54. The flow cell device of aspect 51, wherein the sample injection port is configured to supply the fluid sample as a mist.55. The flow cell device of any one of aspects 51 to 54, wherein the sample injection port comprises a nozzle.56. The flow cell device of any one of aspects 51 to 55, wherein the sample injection port is configured to supply the fluid sample to flow substantially along the direction of gravity.57. The flow cell device of any one of aspects 51 to 55, wherein the sample injection port is configured to supply the fluid sample to flow substantially transverse to the direction of gravity.58. The flow cell device of any one of aspects 51 to 57, wherein the sample injection port comprises a capillary tube.59. The flow cell device of any one of aspects 51 to 58, wherein the flow cell body comprises at least one opening formed therethrough that defines the input optical port and the output optical port.60. The flow cell device of aspect 59, wherein the flow cell body comprises a cavity formed therein that defines the curtain gas channel, and wherein the cavity overlaps and extends across the at least one opening.61. The flow cell device of any one of aspects 51 to 60, wherein the curtain gas channel comprises a single curtain gas flow path that intersects both the input optical port and the output optical port.62. The flow cell device of any one of aspects 51 to 60, wherein the curtain gas channel comprises distinct first and second curtain gas flow paths, the first curtain gas flow path establishing a first gas curtain across the input optical port and the second curtain gas flow path establishing a second gas curtain across the output optical port63. The flow cell device of any one of aspects 51 to 62, wherein the flow of curtain gas along the curtain gas channel is substantially along the direction of gravity.64. The flow cell device of any one of aspects 51 to 62, wherein the flow of curtain gas along the curtain gas channel is substantially against the direction of gravity.65. The flow cell device of any one of aspects 51 to 64, wherein the curtain gas comprises air, nitrogen, or argon.66. The system of any one of aspects 51 to 65, further comprising a curtain gas supply unit configured to supply the curtain gas into the curtain gas channel.67. The flow cell device of aspect 66, wherein the curtain gas supply unit comprises an injection nozzle configured to control the flow of the curtain gas injected into the curtain gas channel.68. The flow cell device of any one of aspects 51 to 67, wherein the flow cell body comprises a base, a cover, and a sidewall extending along a flow cell axis between the base and the cover.69. The flow cell device of aspect 68, wherein the flow cell body has a substantially cylindrical configuration about the flow cell axis.70. The flow cell device of aspect 68 or 69, wherein the sample flow path is substantially parallel to the flow cell axis.71. The flow cell device of aspect 68 or 69, wherein the sample flow path is tilted relative to the flow cell axis in a tilt direction which, in a plane perpendicular to the flow cell axis, points away from the input optical port and / or the output optical port.72. The flow cell device of any one of aspects 68 to 71, wherein the sample injection port extends within the flow cell chamber via an opening formed through the cover and is configured to supply the fluid sample to flow along the sample flow path toward the base.73. The flow cell device of any one of aspects 68 to 72, wherein the input optical port and the output optical port are formed through the sidewall.74. The flow cell device of any one of aspects 68 to 73, wherein an angular separation between the input optical port and the output optical port in a plane perpendicular to the flow cell axis ranges from about 1° to about 20°.75. The flow cell device of any one of aspects 51 to 74, further comprising a sample collector configured to collect the fluid sample after interaction of the fluid sample with the excitation laser light.76. The flow cell device of aspect 75, further comprising a sample discharge port configured to remove the fluid sample from the sample collector.77. The flow cell device of any one of aspects 51 to 76, further comprising an ejection collector configured to collect the sample ejections conveyed along and discharged from the curtain gas channel.78. The flow cell device of any one of aspects 51 to 77, wherein the sample fluid is an aqueous sample.79. The flow cell device of any one of aspects 51 to 78, wherein the sample fluid is a lithium-containing brine.80. The flow cell device of any one of aspects 51 to 78, wherein the sample fluid is a plant nutrient solution.81. The flow cell device of any one of aspects 51 to 80, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid stream flowing within a conduit.82. The flow cell device of any one of aspects 51 to 80, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid contained in a fluid reservoir.83. The flow cell device of any one of aspects 51 to 82, wherein the curtain gas channel is configured to convey the flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.84. A method of performing laser-induced breakdown spectroscopy (LIBS) of a fluid sample, the method comprising: supplying a flow of the fluid sample along a sample flow path within a flow cell chamber; generating excitation laser light along an excitation light path; introducing the excitation laser light into the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma; allowing LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path; detecting the LIBS emission light; and providing a flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path.85. The method of aspect 84, wherein the step of generating the excitation laser light comprises selecting an excitation wavelength of the excitation laser light in a range from about 200 nm to about 2000 nm.86. The method of aspect 84 or 85, wherein deflecting the sample ejections comprises impeding the sample ejections from exiting the flow cell chamber and reaching measurement optics disposed along the excitation light path and the emission light path.87. The method of any one of aspects 84 to 86 wherein the sample flow path is substantially perpendicular to the excitation light path and the emission light path.88. The method of any one of aspects 84 to 87, wherein supplying the flow of the fluid sample comprises supplying the fluid sample as an open-stream flow.89. The method of any one of aspects 84 to 88, wherein supplying the flow of the fluid sample comprises supplying the fluid sample as a laminar flow.90. The method of any one of aspects 84 to 89, wherein supplying the flow of the fluid sample comprises supplying the fluid sample as a mist.91. The method of any one of aspects 84 to 90, wherein providing the flow of curtain gas comprises supplying the flow of curtain gas along a curtain gas channel that intersects the excitation light path and the emission light path.92. The method of aspect 91, further comprising: enclosing the flow cell chamber within a flow cell body; forming at least one opening through the flow cell body to define an input optical port configured to allow the excitation laser light to enter the flow cell chamber and allow the LIBS emission light to exit the flow cell chamber; and forming a cavity inside the flow cell body to define the curtain gas channel, wherein the cavity overlaps and extends the at least one opening.93. The method of aspect 92, further comprising tilting the sample flow path in a tilt direction that points away from the input optical port and / or the output optical port.94. The method of any one of aspects 84 to 92, wherein supplying the flow of the fluid sample comprises supplying the fluid sample substantially along the direction of gravity.95. The method of any one of aspects 84 to 94, further comprising collecting the fluid sample after interaction of the fluid sample with the excitation laser light.96. The method of any one of aspects 84 to 95, further comprising collecting the sample ejections conveyed by the flow of curtain gas.97. The method of any one of aspects 84 to 96, further comprising analyzing the detected LIBS emission light and deriving therefrom analyte information about a presence or absence of one or more constituent elements in the fluid sample.98. The method of aspect 97, wherein the analyte information further comprises a concentration of the one or more constituent elements in the fluid sample.99. The method of any one of aspects 84 to 98, wherein the sample fluid is an aqueous sample.100. The method of any one of aspects 84 to 99, wherein the sample fluid is a lithium-containing brine.101. The method of any one of aspects 84 to 99, wherein the sample fluid is a plant nutrient solution.102. The method of any one of aspects 84 to 101, wherein supplying the flow of the fluid sample comprises: drawing off the fluid sample from a fluid stream flowing within a conduit; and introducing the drawn-off fluid sample into the sample flow path.103. The method of any one of aspects 84 to 102, wherein supplying the flow of the fluid sample along the sample flow path comprises: drawing off the fluid sample from a fluid contained in a fluid reservoir; and introducing the drawn-off fluid sample into the sample flow path.104. The method of any one of aspects 84 to 103, wherein the flow of curtain gas is provided to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.105. The method of any one of aspects 84 to 104, wherein the LIBS analysis is performed in concert with additional analytical methodology.106. The method of aspect 105, wherein the LIBS analysis is performed (i) prior to a secondary analysis, (ii) after a secondary analysis, or (iii) concurrently with a secondary analysis.107. The method of aspect 105, wherein the LIBS analysis and the secondary analysis are performed on the same fluid sample.108. The method of aspect 106 or 107 wherein the secondary analysis is performed using some or all of the spectrophotometric components of the LIBS system.109. The method of aspect 106 or 108, wherein the LIBS and the secondary analysis are performed on separate fluid samples.

[0008] Other method and process steps may be performed prior, during or after the steps described herein. The order of one or more steps may also differ, and some of the steps may be omitted, repeated, and / or combined, as the case may be. It is also to be noted that some steps may be performed using various analysis and processing techniques, which may be implemented in hardware, software, firmware, or any combination thereof.

[0009] Other aspects, features, and advantages of the present disclosure will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the appended drawings. Although specific features described in the above summary and in the detailed description below may be described with respect to specific embodiments or aspects, it should be noted that these specific features may be combined with one another unless stated otherwise.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Fig. 1 is a schematic perspective view of a system for LIBS analysis of a fluid sample, in accordance with an embodiment.

[0011] Fig. 2 is schematic cross-sectional side elevation view of the system of Fig. 1.

[0012] Fig. 3 is a schematic cross-sectional top plan view of the system of Fig. 1.

[0013] Fig. 4 is a schematic perspective view of a flow cell device for use in LIBS analysis, in accordance with an embodiment.

[0014] Fig. 5 is a schematic perspective view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0015] Fig. 6 is a schematic cross-sectional top plan view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0016] Fig. 7 is a schematic cross-sectional side elevation view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0017] Fig. 8 is a schematic cross-sectional side elevation view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0018] Fig. 9 is a schematic cross-sectional side elevation view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0019] Fig. 10 a schematic perspective view of a system for LIBS analysis of a fluid sample, in accordance with another embodiment.

[0020] Figs. 11A and 11B are schematic block diagrams of systems for LIBS analysis of fluid samples, in accordance with other embodiments, where the LIBS systems include multiple flow cells in a parallel (Fig. 11A) or series (Fig. 11B) arrangement.

[0021] Fig. 12 is a flow diagram of a method for LIBS analysis of a fluid sample, in accordance with an embodiment.

[0022] Fig. 13 is a schematic representation of an example direct lithium extraction (DLE) operation in which the disclosed techniques may be implemented, in accordance with an embodiment.

[0023] Fig. 14 shows a LIBS spectrum obtained using a system, device, and method in accordance with an embodiment to analyze a brine solution containing lithium.

[0024] Fig. 15 shows four overlaid LIBS spectra obtained using a system, device, and method in accordance with an embodiment to perform a multi-timepoint analysis of a fluid sample with use of a gas curtain.

[0025] Fig. 16 shows four overlaid LIBS spectra obtained using a system, device, and method in accordance with an embodiment to perform a multi-timepoint analysis of a fluid sample without use of a gas curtain.DETAILED DESCRIPTION

[0026] The present disclosure generally relates to techniques, which include systems, devices, and methods, for characterization and analysis of fluid samples using LIBS. The disclosed techniques can be used in various applications and settings, notably in field-deployed environments where a fluid sample of interest is drawn off a fluid reservoir or diverted from a process flow stream.

[0027] The embodiments disclosed herein generally include or use a flow cell, a laser source, a spectral detection device, measurement optics, and a curtain gas channel. The laser source is configured to generate excitation laser light along an excitation light path. The flow cell defines a flow cell chamber and includes a sample injection port, an input optical port, and an output optical port. The sample injection port is configured to supply a flow of the fluid sample along a sample flow path within the flow cell chamber. The input optical port is configured to allow the excitation laser light to enter the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma and produce LIBS emission light. The output optical port is configured to allow the LIBS emission light to exit the flow cell chamber along an emission light path terminating on the spectral detection device, where the LIBS emission light is detected. The measurement optics, which can include lenses, mirrors, and filters, are disposed along the excitation light path and the emission light path. The curtain gas channel is configured to convey a flow of curtain gas (e.g., compressed air from a nozzle) therealong to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path. The gas flow path extends between the flow cell and the measurement optics to intersect the excitation lightpath and / or the emission light path. The deflection action of the curtain gas flow impedes the sample ejections from reaching the measurement optics. In some embodiments, the curtain gas channel is formed within the sidewall of the flow cell.

[0028] The provision of the curtain gas channel can reduce liquid splashing and drawbacks associated thereto relating to LIBS measurement inaccuracies and disturbances, contamination and damage of measurement optics, and overall performance degradation. In some embodiments, the sample injection port may be configured to supply the fluid sample inside the flow cell chamber as a laminar flow, which can provide advantages in terms of providing a homogenous stream for analysis and reducing liquid splashing at the injector outlet. In some embodiments, the laminar flow may result from a specific sample injection port configuration, for example by use of a capillary tube. In some embodiments, the sample injection port may be configured to supply the fluid sample inside the flow cell chamber as a mist, which may provide advantages in terms of reduction of overall liquid splashing at the injector outlet. In some embodiments, the mist may result from a specific sample injection port configuration, for example by use of a spray nozzle and / or an atomizer.

[0029] The disclosed techniques can find use in various fields of applications and industries that use or may benefit from LIBS for characterization and monitoring of fluid samples. Non-limiting examples of possible fields of use include: mining and geology (e.g. determination of mineral composition of brines and other process fluids, aiding in mineral exploration in liquid resource settings); environmental analysis (e.g., analysis of soil, rocks, and sediments for environmental monitoring and geological studies); wastewater analysis and water quality monitoring (e.g., monitoring changes in water chemistry in natural water bodies, industrial effluents, and drinking water sources); aerospace and defense (e.g., detection of trace elements on surfaces, including explosives and hazardous chemicals, including hazardous liquid waste); forensics (e.g., residue analysis); pharmaceutical (e.g., analysis of pharmaceutical products in liquid process streams, including the identification of specific contaminants); chemical process monitoring (e.g., monitoring composition of chemical process streams, including ensuring that desired chemical reactions are taking place as intended and identifying unwanted byproducts or impurities); food and beverage (e.g., food analysis, including wine and beverage analysis for elemental composition determination and identification of contaminants); nuclear (e.g., monitoring of composition of materials exposed to radiation, analysis of liquid wastes from nuclear facilities for compliance with safety standards and identification of radioactive materials). The disclosed techniques can be implemented in various environments and settings, including on-site and field-deployed operations (e.g., in mining and other industrial applications), manufacturing facilities, research and developmentlaboratories, and the like. Depending on the application, the disclosed techniques can be used with portable or fixed test instruments.

[0030] As required, any implementation of the devices of the present disclosure may be used to analyze solutions requiring pre-treatment. For example, it may be advantageous for signal-to-noise enhancement and reduced downtime for cleaning to have aqueous solutions descendent from plant growth systems to be pretreated to remove microbial content. For example, it may be advantageous to perform liquid-liquid separation on an oil sample to remove hydrocarbons prior to analysis. Any pre-treatment method applicable to a specific sample type may be considered. Pre-treatment may be executed separately, following sample collection and prior to transferring the sample solution to the LIBS flow cell, or pre-treatment may be executed with a separate module directly attached to the LIBS flow cell.

[0031] One more specific example is the field of lithium mining from brines, in particular for LIBS analysis of brine streams produced or otherwise used at various stages of direct lithium extraction (DLE) operations where there are process streams (e.g., eluent, eluate, concentrate, mother liquor, diluent, washwater, recovery, impurity removal) that may change elemental content during operation. Non-limiting examples include: immediately upon extraction from brine water sources; before and after each pre-treatment module for removing impurities and / or adding chemicals; before and after lithium-extraction (e.g., using lithiumselective sorbent-packed columns); before and after water recovery modules; before and after any incoming or outgoing streams of the carbonation module; and before delithiated brine reinjection.

[0032] One more specific example is the field of petroleum extraction and refinement, in particular for LIBS analysis of impurities in crude oil, natural gas, and related processing streams (e.g., fractionation, cracking, reforming, desalting, coking, desulfurization, upgrading). The analyses may be performed on feedstock, product, or both, (e.g., monitoring sulfur content during amine treatment of sour gas streams); to determine total elemental analysis and / or specific impurity monitoring (e.g., monitoring lithium sodium, potassium, beryllium, calcium, magnesium, or any combination thereof during desalting operations); to monitor total impurity content of aqueous waste streams (e.g., discharged cooling water, water separated from crude oil).

[0033] One more specific example is the field of pharmaceutical synthesis, in particular for LIBS analysis of raw material purity, impurities, or both (e.g., analysis of trace metals in palladium catalysts), and / or impurity analysis of synthetic route materials (e.g., starting materials, intermediates, active pharmaceutical ingredients, and / or drug products). For example, synthetic routes employing the use of Suzuki coupling reactions, or similar methodologies wherein a process intermediate may include a borate or boric acid, which may be detected in situ, in process streams, in the final product, or any combination thereof. For example,any synthetic route involving the use of a stoichiometric metal reagent, a metal catalyst, or both (e.g., palladium, nickel, iron, vanadium, tin) wherein the metal may be detected in situ, in process streams, in the final product, or any combination thereof. Solutions may comprise aqueous mixtures, or mixtures with sufficiently low solvent content so as to allow safe execution of analysis. As those skilled in the art will appreciate, different solvent-water mixtures will have different flash points, and each specific solvent-water mixture will have different flash points based on the exact concentration (e.g., v / v%) of solvent.

[0034] One more specific example is the field of agriculture, in particular for LIBS analysis of hydroponic fluid streams. For example, hydroponic operations may perform analysis of the prepared solutions to analyze nutrient content (e.g., nitrates, nitrites, phosphates, phosphites, and sulfates) prior to application within the hydroponic system, during application within the hydroponic system, and / or in waste collection streams.

[0035] In some embodiments, the disclosed techniques can allow LIBS measurements to be carried out on a sample drawn off a fluid reservoir or diverted from a process flow stream. Such measurements may be fully automated and performed without the need for human intervention or sample removal from the process, in contrast to offline and / or batch analyses (e.g., in a laboratory setting). The disclosed techniques may also allow for real-time or continuous process analysis, monitoring, and control. The term "real-time" is used herein as a practical term that refers to measurements that can be conducted with no or no significant time delay.

[0036] The term "fluid sample" refers herein to any substance or medium having the ability to flow that can be characterized by LIBS. The term "fluid" is meant to encompass substances and media of various viscosities, and it may in some instances be used interchangeably with the term "liquid". Fluid samples may be broadly classified as organic, inorganic, or biological. Depending on the circumstances, a fluid sample can refer to a pure substance (e.g., water), a homogeneous solution (e.g., brine) containing one or more solutes dissolved in a solvent, a heterogeneous mixture (e.g., suspension, dispersion, emulsion, slurry, colloid), a cream, a gel, a paste, or the like. Solutions can be aqueous or non-aqueous, and they can use any suitable type of organic or inorganic solvents, including polar protic, polar aprotic, and non-polar solvents with suitable flammability tolerances. More specific examples of possible solvents include long-chain alcohols, heavy glycols, mineral oils, ionic liquids, and deep eutectic solvents.

[0037] Fluid samples can contain one or more analytes of interest. The term "analyte" is intended to refer herein to any LIBS-detectable atomic element present in a fluid sample, whether intentionally or unintentionally (e.g., as an impurity or contaminant). Non-limiting examples of elemental analytes which may be found in brines used in DLE processes include Li, Na, Ca, Mg, Al, K, S, and B, with representativeconcentration ranges as follows: Li: 1 ppm to 4000 ppm; Na: 2 ppm to 100,000 ppm; Ca: 2 ppm to 10,000 ppm; Mg: 1 ppm to 10,000 ppm; Al: 1 ppm to 40 ppm, K: 1 ppm to 50,000 ppm; S: 25 ppm to 10,000 ppm; B: 1 ppm to 1000 ppm.

[0038] In the disclosed techniques, LIBS can be used to provide various types of quantitative and qualitative information about the constituent elements of a fluid sample. Non-limiting examples of information that can be obtained from LIBS spectra include: (i) fluid sample spectral fingerprint, including atom-specific emission lines at wavelengths corresponding to the constituent elements of the sample; (ii) identification of constituent elements in both homogeneous and heterogenous samples, assuming sufficiently high concentrations relative to instrument sensitivity; and (iii) quantitative analysis of homogeneous samples (e.g., concentration of constituent elements) from atomic line intensities. It is appreciated that the basic principles underlying LIBS, including the theory of LIBS and the measurement and analysis of LIBS spectra, are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the disclosed techniques.

[0039] Various aspects and implementations of the present techniques are described below with reference to the figures.

[0040] Referring to Figs. 1 to 3, there are illustrated schematic views of an embodiment of a system 100 for LIBS analysis of a fluid sample 102. As noted above, the fluid sample 102 can include any fluid substance or medium known or expected to contain analytes that can be characterized or monitored using LIBS. For example, in DLE applications, the fluid sample 102 may be a lithium-containing brine stream, a substantially purified lithium process stream, a lithium-depleted impurity stream, a process water recovery stream, or a lithium carbonate product stream.

[0041] Depending on the circumstances or requirements of a given application, the LIBS system 100 can be deployed in various configurations for many purposes and applications relating to fluid sample analysis and monitoring of ongoing processes, conditions, and operations. For example, the LIBS system 100 may be provided along a flow bypass or diversion structure connected to a process flow line (e.g., a flow-through pipe or conduit) through which a stream of the fluid sample 102 is flowing. In other embodiments, the LIBS system 100 may be connected (e.g., along a sample circulation loop or extraction line) to a reservoir (e.g., a reactor or storage vessel) containing the fluid sample 102.

[0042] Broadly described, the LIBS system 100 of Figs. 1 to 3 generally includes a laser source 104, a flow cell 106, excitation optics 108 and collection optics 110, a spectral detection device 112, and a curtain gaschannel 114. The laser source 104 is configured to generate an excitation laser light 116 along an excitation light path 118. The flow cell 106 includes a flow cell body 120 enclosing a flow cell chamber 122. The flow cell 106 also includes a sample injection port 124, an input optical port 126, and an output optical port 128. The sample injection port 124 is configured to supply a flow of the fluid sample 102 along a sample flow path 130 extending within the flow cell chamber 122. The flow cell 106 may be configured for continuous flow or intermittent flow. For example, the flow cell 106 may be configured to allow flow along the sample flow path 130 to be started, stopped, and resumed (at any cadence), and LIBS measurements may be taken while flow is stopped or occurring at any rate. The input optical port 126 is configured to allow the excitation laser light 116 to enter the flow cell chamber 122 along the excitation light path 118 to intersect the sample flow path 130 and energize the fluid sample 102 to form a laser-induced plasma 132 within the flow cell chamber 122. The output optical port 128 is configured to allow LIBS emission light 134 emitted from the laser-induced plasma 132 to exit the flow cell chamber 122 along an emission light path 136. The spectral detection device 112 is disposed along the emission light path 136 and configured to detect the LIBS emission light 134 exiting the flow cell chamber 122. In the illustrated embodiment, the curtain gas channel 114 extends within the flow cell body 120. The curtain gas channel 114 is configured to convey a flow of curtain gas 138 to entrain and deflect sample ejections 140 (e.g., splashing droplets and aerosols) from the laser- induced plasma 132 away from the excitation light path 118 and / or the emission light path 136. The deflected sample ejections 140 are prevented, or at least impeded, from reaching the measurement optics and adversely affect their operation.

[0043] Depending on the application, all or some of the components of the LIBS system 100 may be packaged together in a substantially self-contained housing or container. In some embodiments, the LIBS system 100 may be sold in such a packaged configuration. The packaging of the LIBS system 100 can help prevent foreign matter such as rain, moisture, dust, dirt, debris, and the like, from reaching the system components during field deployments or on-site uses, for example, in industrial or environmental monitoring applications, particularly in open-air conditions. Packaging can also reduce the risks of damaging or causing optical misalignment among the system components as a result of accidental shock or inadvertent mishandling, and may also provide safety measures for nominal operation of laser equipment.

[0044] Referring briefly to Fig. 4, in some embodiments, the flow cell 106 and the curtain gas channel 114 can define a flow cell device 142 configured for use in the LIBS system 100 along with the laser source 104, the measurement optics 108, 110, and the spectral detection device 112. In some embodiments, the LIBS flow cell device 142 may be manufactured and sold as a single unit for use with the laser source 104, the measurement optics 108, 110, and the spectral detection device 112 to form the LIBS system 100.

[0045] Returning to Figs. 1 to 3, the structure, configuration, and operation of these components and other possible components of, or coupled to, the LIBS system 100 are described in greater detail below. It is appreciated that Figs. 1 to 3, and likewise for other figures described below, are meant to provide schematic representations that aim to illustrate a number of components and features of the LIBS system 100, such that additional components and features that may be useful or necessary for practical operation may not be specifically depicted. Non-limiting examples of such additional features and components can include, to name a few, power supplies, electrical connections, optical links and connections (e.g., optical fibers, optical waveguides, free-space optics), optical components (e.g., lenses, mirrors, filters), fluid supply lines (e.g., conduits, such as pipes or tubes), pressure and flow control devices (e.g., pumps, valves, regulators, restrictors), temperature regulator, waste collectors, processors and controllers, and other types of hardware and equipment.

[0046] The flow cell 106 can be embodied by any appropriate fluidic device capable of allowing the fluid sample 102 to flow therewithin along the sample flow path 130 for irradiation of the fluid sample 102 by the excitation laser light 116. The flow cell body 120 may be made of various materials including, but not limited to, polyetheretherketone (PEEK), poly(methyl methacrylate) (PMMA), polysulfone (PSU), polyoxymethylene (POM), polytetrafluoroethylene (PTFE, commonly known by its trade name, Teflon®). For other application cases, stainless steel and / or glass may be used. In some embodiments, the material may be selected primarily for its mechanical and chemical resistance properties and in view of the sample properties (e.g., composition, temperature, pH).

[0047] The flow cell body 120 encloses an interior volume that defines the flow cell chamber 122. The flow cell body 120 generally includes a base 144 and a cover 146 spaced apart from each other, and a sidewall 148 extending along a flow cell axis 150 and interconnecting the base 144 and the cover 146. In the illustrated embodiment, the sample flow path 130 is substantially parallel to the flow cell axis 150 and substantially perpendicular to both the excitation light path 118 and the emission light path 136, but neither is requirement. In particular, the size, shape, orientation, and arrangement of the sample flow path 130 may be varied depending on the circumstances or requirements of a given application. In some embodiments, the flow cell body 120 has a modular construction. Such a construction can be advantageous in terms of improving ease and reducing cost and time of assembly, disassembly, and other maintenance operations, as well as in terms of providing design flexibility and scalability. In some embodiments, the sidewall 148 may be made of a material transparent to the excitation laser light and the LIBS emission light, which can be advantageous in that visualization of the laser focus can aid in optimizing plasma generation (e.g., by adjusting the fluid sample and laser beam positioning). In the illustrated embodiment, the flow cell body 120 has asubstantially cylindrical configuration about the flow cell axis 150, but other arrangements can be used in other embodiments. In some embodiments, the flow cell body 120 may have a height (e.g., defined along the flow cell axis 150) ranging from about 30 mm to about 500 mm, and a diameter (e.g., defined transverse to the flow cell axis 150) ranging from about 30 mm to about 200 mm, although other dimensions may be used in other embodiments.

[0048] I n the illustrated embodiment, the input optical port 126 and the output optical port 128 are provided as two distinct openings formed through the sidewall 148. For example, the input optical port 126 and the output optical port 128 may each have a cross-sectional area ranging from about 2 mm2to about 100 mm2. In other embodiments, the input optical port 126 and the output optical port 128 may be provided as a single opening formed through the sidewall 148, as depicted in the embodiment of Fig. 5.

[0049] Returning to Figs. 1 to 2, the input optical port 126 and the output optical port 128 are disposed at a same axial position relative to the flow cell axis 150, such that the excitation light path 118 and the emission light path 136 are substantially coplanar with each other and substantially perpendicular to the flow cell axis 150. Of course, various other geometries and arrangements of the input optical port 126 and the output optical port 128 are contemplated in other embodiments. For example, in some embodiments, either or both of the excitation light path 118 and the emission light path 136 may be obliquely oriented with respect to the flow cell axis 150. In some embodiments, the angular separation between the input optical port 126 and the output optical port 128 in a plane perpendicular to the flow cell axis 150 can range from 0° to 180°, for example, from about 1° to about 20°. For example, referring briefly to Fig. 6, there is illustrated another embodiment of a LIBS system 100 in which the angular separation between the input optical port 126 and the output optical port 128 in a plane perpendicular to the flow cell axis 150 is about 90°, which is larger than in the embodiment of Figs. 1 to 3. As discussed below, when the angular separation between the input optical port 126 and the output optical port 128 exceeds a certain value, it may be required or beneficial that the curtain gas channel 114 include multiple curtain gas flow paths.

[0050] Returning to Figs. 1 to 3, the sample injection port 124 may be provided as a flow-through conduit. In some embodiments, the flow-through conduit may be a capillary tube. For example, the capillary tube may be made of stainless steel and have an inner diameter ranging from about 1 mm to about 10 mm. It is appreciated, however, that the sample injection port 124 may be of any suitable size, shape, and configuration, which may be selected based on desired or required characteristics of the flow of the fluid sample 102 flowing along the sample flow path 130.

[0051] In the illustrated embodiment, the sample injection port 124 extends between an injector inlet 152 and an injector outlet 154. The injector inlet 152 is disposed outside the flow cell chamber 122, and the injector outlet 154 is disposed inside the flow cell chamber 122. The injector inlet 152 is in fluidic communication with a sample supply source 156 containing the fluid sample 102 via a suitable sample supply line 158. The sample supply line 158 may be, or be part of, a flow diversion line configured to extract or draw out the fluid sample 102 from the sample supply source 156 to the sample injection port 124 for injection within the flow cell chamber 122. In some embodiments, the sample supply source 156 may be a process line (e.g., a conduit, such as a pipe or tube) through which the fluid sample 102 is flowing as part of an ongoing process or operation. In other embodiments, the sample supply source 156 may be a reservoir in which the fluid sample 102 is contained (e.g., for storage, treatment, or processing), also possibly as part of an ongoing process or operation. In either scenario, the ongoing process or operation may be implemented in mining or other industrial or field-deployed applications.

[0052] In some embodiments, the sample injection port 124 is configured to supply the fluid sample 102 along the sample flow path 130 through the cover 146 and toward the base 144. In the illustrated embodiment, the sample injection port 124 can extend within the flow cell chamber 122 via an opening 160 formed through the cover 146 and be configured to supply the fluid sample 120 along the sample flow path 130 to flow toward the base 144. The sample injection port 124 may be held in place by any suitable mounting apparatus 162. In the illustrated embodiment, the sample injection port 124 is configured to supply the fluid sample 102 as an open-stream flow moving vertically downward (i.e., along the direction of gravity) toward the bottom of the flow cell chamber 122. The term "open-stream flow" refers herein to a flow whose surface is open to air rather than enclosed or bounded by a conduit wall. In some embodiments, the sample injection port 124 is configured to supply the fluid sample 102 as a laminar flow, which can provide advantages in terms of providing a homogenous stream for analysis and ensuring both analyte homogeneity (e.g., no air pockets, etc.) and consistent sample analysis. Furthermore, a laminar flow generally has smooth fluid surface characteristics, which can help ensure consistent laser interaction and plasma formation, with the same resultant effect on the analysis. Laminar flow can also reduce liquid splashing that could otherwise occur at the injector outlet 154 as well as reduce the analysis time required to achieve a representative quantitative analysis of the sample. However, this is not a requirement, such that the fluid sample 102 may be supplied as a turbulent flow in other embodiments. In some embodiments, the injector outlet 154 may be positioned at a slightly higher axial position (i.e., closer to the cover 146 of the flow cell body 120) than the input optical port 126, for example, 1 to 10 mm. In such a configuration, irradiation of the fluid sample 102 by the excitation laser light 116 can occur as soon as the fluid sample 102 comes out of the sample injection port 124.

[0053] Returning to Figs. 1 to 3, the flow cell 106 can include a sample collector 164 configured to collect the fluid sample 102 exiting the sample flow path 130 after interaction with the excitation laser light 116. In the illustrated embodiment, the sample collector 164 is located at the bottom of the flow cell 106 to receive the fluid sample 102 moving vertically downward along the sample flow path 130. The sample collector 164 is defined by the base 144 and a lower portion of the sidewall 148. In some embodiments, the sample collector 164 may be sufficiently deep to prevent or at least mitigate back splashing of the fluid sample 102, which could otherwise contaminate the measurement optics 108, 110. In order to further reduce the likelihood of back splashing, the sample collector 164 may include a meshed top portion (not shown). In other embodiments, the sample collector 164 may be provided as a separate component from the flow cell 106, which is configured to be arranged under the base 144 of the flow cell 106. In some embodiments, a space or air gap may exist between the base 144 and the sample collector 164 to provide a path for the curtain gas 138 to escape from the curtain gas channel 114. In other embodiments, the sample collector 164 may be removably attached to the flow cell 106 to allow for the use of different sample collectors, which can be useful to ensure compatibility between the fluid sample composition and the collector material.

[0054] In some embodiments, the flow cell 106 can include a sample discharge port 166 configured to remove, continuously or in batches, the fluid sample 102 collected in the sample collector 164. In some embodiments, the sample discharge port 166 may be in fluidic communication with the sample supply source 156 and configured to return the fluid sample 102 back to the sample supply source 156 after passage of the fluid sample 102 through the flow cell 106 for LIBS analysis. In other embodiments, the sample discharge port 166 may be in fluidic communication with a sample processing unit for further processing of the LIBS-analyzed fluid sample 102 (e.g., treatment, reuse, recycling, discharge, or disposal). In yet other embodiments, the flow cell 106 may not include a dedicated sample discharge port. In such a case, the fluid sample 102 can be removed from the sample collector 164 by disassembling the sample collector 164 from the flow cell 106, emptying the disassembled sample collector 164, and reassembling the empty sample collector 164 back into the flow cell 106.

[0055] In some embodiments, the LIBS system 100 may include a sample pump assembly 168 in fluidic communication with the sample injection port 124 and configured to control a flow of the fluid sample 102 along the sample flow path 130. The sample pump assembly 168 can be used in applications with insufficient line or head pressure, or in applications where it is desired or required that the fluid sample 102 be injected within the flow cell chamber 122 as a pressurized stream.

[0056] In some embodiments, the fluid sample 102 may be conveyed a single time through the flow cell 106.Such embodiments can be referred to as single-pass or open-circuit implementations. In other embodiments,the same stream of fluid sample 102 may be conveyed multiple times through the flow cell 106. Such embodiments can be referred to as multiple-pass or closed-circuit implementations. In such implementations, the fluid sample 102 exiting the flow cell 106 via the sample discharge port may be returned to the sample injection port 124 via a sample recirculation line to re-enter the flow cell 106 and go through another LIBS acquisition cycle.

[0057] Referring still to Figs. 1 to 3, the laser source 104 can be embodied by any appropriate device or combination of devices capable of generating the excitation laser light 116 with beam characteristics suitable for use in LIBS. In some embodiments, the laser source 104 is a diode- or lamp-pumped, pulsed, solid-state Nd:YAG laser source. However, various other types of laser sources can be used in other embodiments. Nonlimiting examples of laser sources that can be used in LIBS spectroscopy include solid-state lasers, including bulk crystal lasers and fiber lasers; semiconductor lasers, including laser diodes; gas lasers, including excimer lasers and ion lasers; and dye lasers.

[0058] In some embodiments, the laser source 104 may be configured to emit the excitation laser light 116 in the visible, ultraviolet, or near-infrared range of the electromagnetic spectrum. For example, in some embodiments, the excitation laser light 116 may have an excitation wavelength lying within a waveband ranging from about 200 nm to about 2000 nm. Non-limiting examples of excitation wavelengths commonly used in LIBS for DLE applications include 213 nm, 266 nm, 355 nm, 532 nm, and 1064 nm. In some embodiments, the excitation laser light 116 may have the following parameters: a beam diameter ranging from about 2 mm to about 20 mm; a pulse width ranging from about 5 ns to about 20 ns; a pulse repetition rate ranging from about 1 to about 20 Hz; and a pulse energy ranging from about 1 to about 300 mJ, in particular, from about 10 to about 100 mJ.

[0059] The laser source 104 may be selected based on various factors. Non-limiting examples of such factors include, to name a few, the excitation wavelength; the spectral linewidth and purity; the frequency stability; the beam quality; the output power and power stability; pulse characteristics such as the peak power, repetition rate, duration, and temporal shape; and the compactness, reliably, ruggedness, and cost. It is appreciated that the theory, instrumentation, and operation of laser sources used in LIBS applications are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the disclosed techniques.

[0060] Referring still to Figs. 1 to 3, the excitation optics 108 are configured to relay the excitation laser light 116 from the laser source 104 to within the flow cell chamber 122 via the input optical port 126, and the collection optics 110 are configured to relay the LIBS emission light 134 from within the flow cell chamber 122to the spectral detection device 112 via the output optical port 128. The excitation optics 108 and the collection optics 110 will be referred to herein collectively as measurement optics 108, 110. In the illustrated embodiment, the measurement optics 108, 110 are provided outside the flow cell body 120, with the excitation optics 108 arranged between the laser source 104 and the input optical port 126, the collection optics 110 arranged between the spectral detection device 112 and the output optical port 128. However, in other embodiments, it is contemplated that the excitation optics 108 and / or the collection optics 110 may include one or more components inside the flow cell chamber 122.

[0061] The measurement optics 108, 110 can include any number of optical components configured to direct, shape, filter, split, focus, collimate, expand, or otherwise condition or act on the excitation laser light 116 and the LIBS emission light 134. Non-limiting examples of optical components that can be used as part of the measurement optics 108, 110 include lenses, reflectors, spectral filters, beamsplitters, prisms, diffraction gratings, and optical fibers and waveguides. In some embodiments, the excitation optics 108 can include one or more focusing lenses (e.g., an achromatic triplet) configured to focus the excitation laser light 116 onto the fluid sample 102 to increase the irradiance and favor plasma formation. The collection optics 110 can also include one or more lenses (e.g., a collimating and focusing lens pair) configured to collect the LIBS emission light 134 exiting the flow cell chamber 122 along the emission light path 136, followed by fiber optics configured to deliver the LIBS emission light 134 to the spectral detection device 112. Various types of lens materials having a suitably high transmittance and a suitably high laser induced damage threshold (LIDT) can be used. Non-limiting examples include fused silica and borosilicate crown glass. The measurement optics 108, 110 can also include one or more mirrors to direct the excitation laser light 116 and / or the LIBS emission light 134 along their respective light paths 118, 136, as well as one or more spectral filters configured to selectively control the spectral content of the excitation laser light 116 and / or the LIBS emission light 134. Depending on the application, the measurement optics 108, 110 may include free-space optics only, or a combination of free-space optics and fiber optics.

[0062] The spectral detection device 112 is disposed along the emission light path 136 to receive the LIBS emission light 134 collected the collection optics 110. The spectral detection device 112 can be embodied by any device or combination of devices capable of measuring a spectrally dependent response of an optical signal over a specified spectral range. In the illustrated embodiment, the spectral detection device 112 includes a spectrometer 170 and an optical detector 172.

[0063] The spectrometer 170 operates as a wavelength selector configured to spatially split and disperse the LIBS emission light 134 into a plurality of spectral components, and to direct the plurality of spectral components onto the optical detector 172 along a respective plurality of spatially distinct detection paths.Various spectrometer types and designs are available, which generally use prisms or diffraction gratings. Nonlimiting examples include Littrow, Paschen-Runge, Echelle, and Czerny-Turner spectrometers. In some embodiments, spectrometers having a high spectral resolution and a broad wavelength coverage are desirable.

[0064] The optical detector 172 can be embodied by a photodetector array configured to detect the plurality of spectral components received from the spectrometer 170 and generate therefrom a plurality of output signals. Various types and designs of photodetector arrays capable of measuring a spatial distribution of light intensity can be used. Non-limiting examples include charge-coupled device (CCD) arrays, photodiode (PD) arrays, avalanche photodiodes (APD) arrays, photomultiplier tube (PMT) arrays, and complementary metal- oxide-semiconductor (CMOS) arrays. In some embodiments, optical detectors with a large dynamic range and a high quantum efficiency over a wide wavelength range are desirable to cover a large number of elements over a large range of elemental concentrations.

[0065] In some embodiments, the spectral detection device 112 may be configured to operate within a LIBS emission wavelength range extending from about 200 nm to about 2000 nm, with a resolution ranging from about 0.001 nm to about 0.5 nm, although values outside these ranges are possible in other embodiments. It is appreciated that the theory, instrumentation, and operation of spectrometers and optical detectors commonly used in LIBS are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the disclosed techniques. It is also appreciated that in embodiments where the fluid sample 102 includes only one or a few constituent elements, the spectral detection device 112 may include a bandpass filter and a single-channel optical detector (e.g., a PD or a PMT), rather than a spectrometer and an arrayed optical detector (e.g., a CCD array).

[0066] Referring still to Figs. 1 to 3, in operation of the LIBS system 100, the excitation laser light 116 is directed within the flow cell chamber 122 along the excitation light path 118 to intersect the sample flow path 130 and energize the fluid sample 102 to form a laser-induced plasma 132. In the laser-induced plasma 132, the constituent elements of the fluid sample 102 are excited to a higher-energy state, and then return to a lower-energy state. This excitation-relaxation process produces LIBS emission light 134, whose spectrum is characteristic of the elements present in the fluid sample 102. The LIBS emission light 134 is collected along the emission light path 136 and detected by the spectral detection device 112 for elemental analysis. The theory of LIBS— including the physics involved in the processes of laser ablation, plasma formation, and atomic emission— is generally known in the art and need not be described in detail herein other than to facilitate an understanding of the disclosed techniques.

[0067] As noted above, a challenge in the application of LIBS to fluid sample analysis is the generation of sample ejections 140, such as splashes of droplets and aerosols, from the laser-induced plasma 132 as a result of laser-sample interactions. If left uncontrolled, the sample ejections 140 reach the measurement optics 108, 110 disposed along the excitation and emission light paths 118, 136. This is the case even if the measurement optics 108, 110 are located outside the flow cell chamber 122, since the sample ejections 140 can escape from the flow cell chamber 122 via the input and output optical ports 126, 128. The deposition and accumulation of sample ejections 140 on the measurement optics 108, 110 can result in contamination, damage, failure, or otherwise reduced or altered performance. These issues can in turn lead to undesirably frequent cleaning, repair, replacement, or other maintenance operations. The sample ejections 140 can also interfere with LIBS emission light 134 and introduce errors in the LIBS analysis.

[0068] In the disclosed techniques, the curtain gas channel 114 is configured to convey a flow of curtain gas 138 to deflect at least part of the sample ejections 140 emanating from the laser-induced plasma 132 away from the excitation light path 118 and / or the emission light path 136, and thus to impede the sample ejections 140 from reaching the measurement optics 108, 110. Depending on the application, the curtain gas channel 114 may be configured to deflect sample ejections 140 emanating from the laser-induced plasma 132 away from the excitation light path 118 only, away from the emission light path 136, or away from both the excitation light path 118 and the emission light path 136. For example, in some embodiments, the excitation optics 108 and the emission optics 110 may be arranged in such a way that only one of the two would need or benefit from the curtain gas channel 114 (e.g., due to being sufficiently far away from the flow cell 106). The curtain gas 138 may be any gas or combination of gases enabling the generation of a curtain gas flow capable of deflecting the sample ejections 140 emanating from the laser-induced plasma 132. Non-limiting examples of curtain gases include, to name a few, air, nitrogen, and argon. In some embodiments, the curtain gas 138 may be subjected to a purification process (e.g., for removal of impurities and contaminants) prior to being injected inside the curtain gas channel 114.

[0069] In the illustrated embodiment, the curtain gas channel 114 extends between a curtain gas inlet 174 and a curtain gas outlet 176. The curtain gas inlet 174 and the curtain gas outlet 176 may each be provided as an opening or orifice defined in the flow cell body 120, and may each be of any suitable size, shape, and configuration, which may be selected based on desired or required characteristics of the flow of curtain gas 138. It is appreciated that the shape, size, and configuration of the curtain gas channel 114 may be varied depending on the circumstances or requirements of a given application.

[0070] In the illustrated embodiment, the curtain gas inlet 174 is arranged at the cover 146 of the flow cell body 120, and the curtain gas outlet 176 is arranged at the base 144 of the flow cell body 120. The curtaingas channel 114 is formed inside the sidewall 148 of the flow cell body 120 and extends along a curtain gas flow direction that is substantially parallel to the flow cell axis 150 and substantially perpendicular to both the excitation light path 118 and the emission light path 136. More specifically, the sidewall 148 includes an inner wall portion 178, an outer wall portion 180, and an intermediate wall portion 182 interposed between the inner wall portion 178 and the outer wall portion 180. In this arrangement, the curtain gas channel 114 is provided as a cavity formed in the intermediate wall portion 182, with an annular-sector-shaped cross-section in a plane perpendicular to the flow of curtain gas 138. By arranging the cavity to overlap with the sidewall openings defining the input and output optical ports 126, 128, the curtain gas channel 114 is configured to establish a gas curtain across the input and output optical ports 126, 128. In this way, sample ejections 140 that could otherwise exit the flow cell chamber 122 through the input and output optical ports 126, 128 and reach the measurement optics 108, 110 are instead entrained along the curtain gas channel 114 by the flow of curtain gas 138 and deflected away from the excitation and emission light paths 118, 136. In other embodiments, the curtain gas channel 114 may extend inside or outside the flow cell chamber 122, rather than within the sidewall 148.

[0071] In the illustrated embodiment, the curtain gas 138 is configured to flow vertically downward, along the direction of gravity. However, in other embodiments, such as that shown in Fig. 7, the curtain gas 138 may be configured to flow upward, against the direction of gravity, with the curtain gas inlet 174 arranged at the base 144 and the curtain gas outlet 176 arranged at the cover 146 of the flow cell body 120. The configuration illustrated in Fig. 7 can be advantageous in terms of reduced splashing (e.g., by eliminating or at least reducing back-splashing from the sample collector 164).

[0072] Returning to Figs. 1 to 3, in the illustrated embodiment, the curtain gas channel 114 includes a single curtain gas flow path providing a gas curtain that extends across both the input optical port 126 and the output optical port 128. However, in other embodiments, such as that shown in Fig. 6, the curtain gas channel 114 may be provided as two separate curtain gas flow paths 184i, 1842, namely, a first curtain gas flow path 184i establishing a first gas curtain across the sidewall opening defining the input optical port 126, and a second curtain gas flow path 1842establishing a second gas curtain across the sidewall opening defining the output optical port 128. Depending on the application, the two curtain gas flow paths 184i, 1842may or may not be coupled to the same curtain gas supply unit. The curtain gas channel 114 having a two-path configuration illustrated in Fig. 6 can be advantageous in terms of overall reduced splashing by application of multiple gas curtains.

[0073] Returning to Figs. 1 to 3, the LIBS system comprises, or is coupled with, a curtain gas supply unit 186 configured to supply the curtain gas 138 into the curtain gas channel 114. The curtain gas supply unit 186 caninclude a curtain gas source 188 configured to store the curtain gas 138. The curtain gas source 188 can be embodied by a gas storage tank or any suitable gas dispensing container. The curtain gas supply unit 186 can also include a curtain gas supply line 190 connected between the curtain gas source 188 and the curtain gas inlet 174 to allow the curtain gas 138 to enter and flow along the curtain gas channel 114. In some embodiments, the curtain gas supply line 190 may include one or more injection nozzles 192. The one or more injection nozzles 192 are connected to the curtain gas inlet 174 and configured to control the flow of the curtain gas 138 injected into the curtain gas channel 114. Non-limiting examples of controllable injection parameters include the flow rate (e.g., 5-150 ml / min), velocity, direction, size (e.g., 1-5 mm flow diameter) and shape, and pressure.

[0074] The curtain gas supply unit 186 can also include various additional flow control devices (not shown), for example, valves, pumps, regulators, and restrictors configured to control the introduction of the curtain gas 138. It is appreciated that various configurations and arrangements are contemplated for the curtain gas supply unit 186, and that various gas injection techniques can be used to provide a suitable gas curtain configured to deflect sample ejections 140 away from the measurement optics 108, 110. In particular, various types of injection nozzles exist and can be used to implement the disclosed techniques, for example, to achieve laminar curtain gas flow.

[0075] It is appreciated that the curtain gas 138 may be supplied into the curtain gas channel 114 either in a blow mode, wherein the curtain gas 138 is pushed into the curtain gas channel 114, or a suction mode, wherein the curtain gas is pulled into the curtain gas channel 114. In addition, the curtain gas 138 may flow along the curtain gas channel 114 substantially either in the same as, or in the opposite direction to, the flow of the fluid sample 102 along the sample flow path 130. The former arrangement is depicted in the embodiment of Figs. 1 to 3, while the latter arrangement is depicted in the embodiment of Fig. 7.

[0076] Returning to Figs. 1 to 3, the curtain gas 138 discharged at the curtain gas outlet 176 may be processed in different ways. For example, the curtain gas 138 may be recycled back into the curtain gas channel 114 via a suitable recycle unit, recovered and stored for another use, or simply discarded. Various approaches can be used to separate the curtain gas 138 from the sample ejections 140 at the curtain gas outlet 176. In some embodiments, an air gap can be provided between the base 144 of the flow cell 106 and the sample collector 164, as noted above. In sealed applications, it can be envisioned to use a pressure release valve going to an air-specific vent, itself leading to a recovery system or atmosphere. A screen or filter may be provided to block sample ejections 140. In the embodiment of Figs. 1 to 3, the sample ejections 140 deflected by the flow of curtain gas 138 are directed into the same sample collector 164 as the fluid sample 102. However, in other embodiments, such as the one depicted in Fig. 8, the sample ejections 140exiting the curtain gas channel 114 at the curtain gas outlet 176 may be collected in a dedicated ejection collector 194 (e.g., including an ejection discharge port 202) and be processed independently from the fluid sample 102.

[0077] Referring to Fig. 9, there is illustrated another embodiment of a system 100 for LIBS analysis of a fluid sample 102. The embodiment of Fig. 9 shares many features with the embodiment of Figs. 1 to 3, which need not be described again, but differs in that the sample flow path 130 is tilted relative to the flow cell axis 150. The tilt is such that, in a plane perpendicular to the flow cell axis 150, the sample flow path 130 is oriented in a tilt direction pointing substantially away from the input optical port 126 and / or the output optical port 128. Tilting of the sample flow path 130 can be achieved by adjusting the arrangement and configuration of the sample injection port 124. By tilting the sample flow path 130 in this manner, the laser-induced plasma 132 is generated farther away from the input optical port 126 and the output optical port 128, such that the sample ejections 140 have to travel a longer distance across the flow cell chamber 122 to reach the input optical port 126 and the output optical port 128. This results in a smaller proportion of the sample ejections 140 having to be deflected by the flow of curtain gas 138, and thus in a reduced likelihood that some of the sample ejections 140 will be able to pass through the curtain gas channel 114 undeflected and to reach the measurement optics 108, 110.

[0078] Referring to Fig. 10, there is illustrated another embodiment of a system 100 for LIBS analysis of a fluid sample 102. This embodiment shares several features with the embodiment of Figs. 1 to 3, but differ in the relative arrangements of the excitation light path 118, the emission light path 136, the sample flow path 130, and the curtain gas channel 114. Namely, in the embodiment of Fig. 10, the sample flow path 130 and the emission light path 136 extend substantially horizontally (i.e., transverse to the direction of gravity), while the excitation light path 118 extends substantially vertically (i.e., along the direction of gravity) between the excitation optics (i.e., a mirror) and the input optical port 126.

[0079] Referring to Figs. 11A and 11B, there are illustrated schematic block diagrams of two other embodiments of systems 100 for LIBS analysis of a fluid sample 102 taken from a sample supply source 156. In each of these two embodiments, the LIBS system 100 includes multiple flow cells 106, each of which coupled to its own laser source 104, spectral detection device 112, measurement optics 108, 110, and curtain gas channel 114. The embodiments of Fig. 11A and 11B can be used to perform concurrent (Fig. 11A; parallel arrangement of the multiple flow cells 106) or sequential (Fig. 11B; series arrangement of the multiple flow cells 106) LIBS analysis on the same sample stream. The embodiments of Figs. 11A and 11B can be useful for analyzing fluid samples with complex sample matrices and / or extensive analyte lists, as each flow cell 106 can be used for analyzing one or a reduced number of analytes contained in the sample. Depending on theapplication, the different flow cells may or may not be identical to another, and likewise for the devices and components coupled thereto.

[0080] Returning to Figs. 1 to 3, the LIBS system 100 may further include a computer device 196. The computer device 196 is configured to control, monitor, and / or coordinate the functions and operations of various components of the LIBS system 100, for example, the laser source 104, the spectral detection device 112, and the curtain gas channel 114. The computer device 196 may also be configured to analyze LIBS detection signals generated by the spectral detection device 112 to derive therefrom analyte information about the elemental composition of the fluid sample 102. Various approaches can be used depending on the sample complexity (e.g., the number of analytes), the volume of data, and the specific instrumentation being used. In some embodiments, the analysis can be carried out using dedicated LIBS analysis software. In some embodiments, the analyte information can include qualitative information about a presence or absence of one or more elements in the fluid sample 102 and / or quantitative information about the amount or concentration of one or more elements present in the fluid sample 102. In some embodiments, the computer device 196 can process the LIBS detection signals into a LIBS spectrum, which is a plot of LIBS emission intensity versus atomic emission wavelength. A LIBS spectrum contains a number of peaks or bands (i.e., a subset of partly overlapping peaks). Each peak represents a specific atomic emission line representative of a constituent element of the fluid sample 102. The position of each peak can be used for elemental identification, while the peak intensity can be related to the corresponding elemental concentration. Other peak parameters, such as the peak linewidth and shape, can also be considered in LIBS spectrum analysis. LIBS elemental identification can be carried out by matching measured spectral signatures with reference spectral signatures stored in a LIBS spectrum library or previously obtained experimentally. Peak deconvolution techniques can be applied to resolve overlapping peaks in complex or multielement samples. It is appreciated that the principles underlying LIBS spectrum analysis to derive elemental information about a sample under test are generally known in the art and need not be described in detail herein other than to facilitate an understanding of the disclosed techniques.

[0081] The computer device 196 can be implemented in hardware, software, firmware, or any combination thereof, and be connected to various components of the LIBS system 100 via wired (e.g., USB-based) or wireless communication links to send and / or receive various types of signals, such as timing signals, control signals, measurement signals, and data signals. The computer device 196 may be controlled by direct user input and / or by programmed instructions, and may include an operating system for controlling and managing various functions of the LIBS system 100. Depending on the application, the computer device 196 may be fully or partly integrated with, or physically separate from, the other hardware components of the LIBS system 100.For example, in some embodiments the functions of the computer device 196 relating to the analysis of LIBS spectra data may be fully or partly integrated into the spectral detection device 112. In some embodiments, the computer device 196 may include a distributed and / or cloud computing network. In the embodiment illustrated in Figs. 1 to 3, the computer device 196 generally includes a processor 198 and a memory 198.

[0082] The processor 198 may be able to execute computer programs, also generally known as commands, instructions, functions, processes, software codes, executables, applications, and the like. While the processor 198 is depicted in Fig. 1 as a single entity for illustrative purposes, the term "processor" should not be construed as being limited to a single processor, and accordingly, any known processor architecture may be used. In some embodiments, the processor 198 may include a plurality of processing units. Such processing units may be physically located within the same device, or the processor 198 may represent processing functionality of a plurality of devices operating in coordination. For example, the processor 198 may include or be part of a computer; a microprocessor; a microcontroller; a coprocessor; a central processing unit (CPU); a special-purpose programmable logic device, such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC); and / or any other devices configured to electronically process information and to operate collectively as a processor. In some embodiments, the processor 198 can include a multicore processor having enough processing power to handle the computational tasks associated with LIBS analysis, including data processing, spectral fitting, and data interpretation. In some embodiments, using a graphics processing unit (GPU) can be helpful in reducing the LIBS analysis run time, particularly for complex data processing or machine-learning-based analysis.

[0083] The memory 200 is a non-transitory and tangible computer product capable of storing computer programs, executable instructions, and other data to be retrieved by the processor 198 for the implementation of various steps of the techniques disclosed herein. The memory 200 may be any computer data storage device or assembly of such devices, including a random-access memory (RAM); a dynamic RAM; a read-only memory (ROM); a magnetic storage device; an optical storage device; a solid-state drive (SSD) device, such as a flash drive memory; and / or any other non-transitory memory technologies. The memory 200 may be coupled to, or included in, the processor 198. While the memory 200 is depicted in Fig. 1 as a single entity for illustrative purposes, the term "memory" should not be construed as being limited to a single memory unit, and accordingly, any known memory architecture may be used. In some embodiments, the memory 200 may include a plurality of memory units. Such memory units may be physically located within the same device, or the memory 200 can represent the functionalities of a plurality of devices operating in coordination.

[0084] Referring to Fig. 12, there is illustrated a flow diagram of a method 300 of performing LIBS analysis of a fluid sample. The fluid sample can be any suitable sample that can be analyzed by LIBS spectroscopy, for example, an aqueous sample such as lithium-containing brine. The method 300 of Fig. 12 may be implemented in a LIBS system or LIBS flow cell device such as those described above, or other suitable systems and devices. It is noted that method 300 may share many features similar to those described with respect to structure, configuration, and operation of system implementations. Such similar features need not be described again below.

[0085] The method includes a step 302 of supplying a flow of the fluid sample along a sample flow path within a flow cell chamber of a flow cell. The flow cell may be of various constructions, such as described above. In some embodiments, the supplying step 302 can include supplying the fluid sample as an openstream flow. The flow of fluid sample may be pressurized or not, and may be under laminar or turbulent conditions. In some embodiments, the fluid sample may be supplied to flow substantially along the direction of gravity, but this is not a requirement.

[0086] In some embodiments, the fluid sample may be taken from a process stream flowing within a conduit (e.g., a primary stream, a slip stream, a utility stream, a byproduct stream, a waste stream). In such embodiments, the supplying step 302 can include an operation of drawing off the fluid sample from a fluid stream flowing within a conduit, and an operation of introducing the drawn-off fluid sample into the sample flow path. In some variants, the method 300 can include an operation of collecting the fluid sample after LIBS analysis, and an operation of reintroducing the collected fluid sample back into the fluid stream. In other variants, the discharged fluid sample is not reintroduced into the fluid stream.

[0087] In other embodiments, the fluid sample may be taken from a fluid contained in a reservoir (e.g., a reaction or storage vessel). The fluid in the reservoir may, but need not, be under stagnant or near stagnant conditions. In such embodiments, the supplying step 302 can include an operation of drawing off the fluid sample from the fluid contained in a fluid reservoir, and an operation of introducing the drawn-off fluid sample into the sample flow path. In some variants, the method 300 can include an operation of collecting the fluid sample after LIBS analysis, and an operation of reintroducing the collected fluid sample back into the fluid reservoir. In other variants, the discharged fluid sample is not reintroduced into the fluid reservoir.

[0088] The method 300 also includes a step 304 of generating excitation laser light along an excitation light path, and a step 306 of introducing the excitation laser light into the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma.The excitation laser light may have an excitation wavelength ranging from about 200 nm to about 2000 nm.In some embodiments, the excitation light path may be substantially perpendicular to the sample flow path.

[0089] The method 300 further includes a step of 308 allowing LIBS emission light emitted from the laser- induced plasma to exit the flow cell chamber along an emission light path, and a step 310 of detecting the LIBS emission light along the emission light path. The detected LIBS emission light can be analyzed by LIBS analysis techniques to derive and deriving therefrom analyte information about the presence or absence of one or more constituent elements in the fluid sample. In some embodiments, the analyte information can further include a concentration of the one or more constituent elements in the fluid sample.

[0090] The method 300 also includes a step 312 of providing a flow of curtain gas to deflect sample ejections (e.g., splashing droplets and aerosols) emanating from the laser-induced plasma away from the excitation light path and / or the emission light path. In some embodiments, deflecting the sample ejections can include impeding the sample ejections from exiting the flow cell chamber and reaching measurement optics disposed along the excitation light path and the emission light path. In some embodiments, the providing step 312 can include supplying the flow of curtain gas along a curtain gas channel that intersects the excitation light path and the emission light path. In some embodiments, the flow cell chamber enclosed within a flow cell body of the flow cell, and the method 300 can include forming (i) at least one opening through the flow cell body to define an input optical port configured to allow the excitation laser light to enter the flow cell chamber and allow the LIBS emission light to exit the flow cell chamber, (ii) a cavity inside the flow cell body to define the curtain gas channel, wherein the cavity overlaps and extends across a cross-sectional area of the at least one opening. In some embodiments, the method 300 can include an operation of collecting the sample ejections conveyed by the flow of curtain gas. Depending on the application, the deflected sample ejections and the analyzed fluid sample may be collected in the same or in different collectors.

[0091] In some embodiments, one or more secondary analyses may be performed on the fluid sample. The secondary analysis may include, but is not limited to, ultraviolet visible spectroscopy, Raman spectroscopy, inductively coupled plasma optical emission spectrometry, and / or inductively coupled plasma mass spectrometry. Such a secondary analysis may be executed prior to the LIBS analysis. For example, a specific secondary analysis may be executed ahead of a LIBS analysis due to overall process constraints (e.g., analysis equipment limitations, installation piping and flow design) and / or to generate data in support of the LIBS analysis (e.g., to determine analyte and / or matrix information to complement LIBS data processing). When necessary (e.g., due to the nature of the of the secondary analysis, wherein the secondary analysis is destructive and / or significantly modifies the analytes or fluid matrix) the LIBS analysis may optionallyperformed on a separately, such as on an isolated fluid sample stream and / or a second fluid sample aliquot. The LIBS analysis and secondary analysis may also be performed on the same fluid sample. For example, each analysis may be executed in either order on a single fluid sample stream (e.g., LIBS analysis followed by secondary analysis, or secondary analysis followed by LIBS analysis) and / or a single sample aliquot. Where both analyses employ similar components (e.g., optical lenses, emission source, detector array) it is possible for both analyses to use the same components and be performed in the same flow cell.

[0092] As noted above, some implementations of the techniques disclosed herein can be used for LIBS characterization and analysis of various fluid samples produced or otherwise used at different stages of DLE operations. Fig. 13 shows a schematic example of a DLE operation 700 in which the present techniques may be used. It is appreciated that the DLE operation 700 depicted in Fig. 13 is for purposes of illustration only, and that various other DLE operation configurations, including more, fewer, or different components, are contemplated.

[0093] The DLE operation 700 generally includes a pretreatment technology 702, a sorbent technology 704, a boron removal technology 706, a water recovery technology 708, a polishing technology 710, a carbonation technology 712, and finishing technologies 714. In the DLE operation 700, brine flows into the pretreatment technology 702 via flow path 716 where it is converted into pre-treated brine, which flows into the sorbent technology 704 via flow path 718. The sorbent technology 704 provides lithium-depleted brine which may be stored, discarded, or recycled via flow path 719. The sorbent technology 704 also provides lithium eluate, which flows to the boron removal technology 706 via flow path 720. The boron removal technology 706 provides boron-lean lithium eluate, which flows to the water recovery technology 708 via flow path 722. The water recovery technology 708 provides lithium concentrate, which flows to the polishing technology 710 via flow path 724. The polishing technology 710 provides polished lithium concentrate, which flows to the carbonation technology 712 via flow path 726. The carbonation technology 712 provides lithium carbonate, which may be dried, filtered, rinsed, recrystallized, or otherwise purified by the finishing technologies 714. The DLE operation 700 also includes a recycle loop 728 from the water recover technology 708 to the sorbent technology 704. In this recycle loop 728, recovered water is used as eluent, which may be supplemented with makeup water via flow path 730.

[0094] In DLE, pretreatment technologies are generally employed to remove gases, remove fine particle solids, reduce total dissolved solids, remove specific impurities (such as arsenic, iron, and / or silica), separate aqueous / non-aqueous phases, adjust inlet pH, and / or adjust inlet temperature. Pretreatment technologies, such as the pretreatment technology 702 depicted in Fig. 13, are generally known in the art and are notdiscussed in detail in the present disclosure. Those skilled in the art will appreciate that pretreatment technologies may be deployed in various positions within a DLE operation or may not be required at all. The systems, devices, and / or methods of the present disclosure may improve pretreatment processing by, for example, detecting lithium and / or determining the presence or concentration of elemental contaminants (including, but not limited to, sodium, potassium, calcium, magnesium, nickel, sulfur) in flow path 716 and 718. The results may be used to optimize the pretreatment technology 702 and / or to ensure the composition in the flow path 718 is within tolerance limits for the sorbent technology 704.

[0095] In DLE, sorbent technologies are generally employed to selectively extract lithium. Sorbent technologies, such as the sorbent technology 704 depicted in Fig. 13, are generally known in the art and are not discussed in detail in the present disclosure. Those skilled in the art will appreciate that pretreatment technologies may be deployed in various positions within a DLE operation or may not be required at all. The systems, devices, and / or methods of the present disclosure may improve sorbent technologies by, for example, detecting lithium and / or determining the presence or concentration of elemental contaminants (including, but not limited to, sodium, potassium, calcium, magnesium, nickel, sulfur) in flow path 718, 719, and 729. The results may be used to optimize the sorbent technology 704 and / or to ensure the composition in the flow path 720 is within tolerance limits for the boron removal technology 706.

[0096] In DLE, boron removal technologies are generally employed to remove boron containing compounds, such as boric acid (B(OH)3), borate anion ([B(OH)]4-), and polyborate ([B3O3(OH)4]“ and / or [B3O3(OH)5]2”), from lithium containing solutions, for example, by ion exchange. Boron removal technologies, such as the boron removal technology 706, are generally known in the art and are not discussed in detail in the present disclosure. Those skilled in the art will appreciate that boron removal technologies may be deployed in various positions within a DLE operation or may not be required at all. For example, the boron removal technology 706 depicted in Fig. 13 may be positioned upstream of the sorbent technology 704, downstream of the water recovery technology 708, or otherwise positioned within the DLE operation 700. The systems, devices, and / or methods of the present disclosure may improve boron removal processing by, for example, determining the concentration of boron in flow path 720 and / or 722. The results may be used to optimize the boron removal technology 706 and / or to ensure the composition in the flow path 722 is within tolerance limits for the water recovery technology 708.

[0097] In DLE, polishing technologies are generally employed to remove magnesium and calcium from lithium-containing solution, for example, by addition of caustic and oxalic acid. Polishing technologies, such as the polishing technology 710 depicted in Fig. 13, are generally known in the art and are not discussed indetail in the present disclosure. Those skilled in the art will appreciate that polishing technologies may be deployed in various positions within a DLE operation or may not be required at all.

[0098] In DLE, carbonation technologies are generally employed to precipitate lithium carbonate from solution, for example by addition of sodium carbonate. Carbonation technologies, such as the carbonation technology 712 depicted in Fig. 13, are generally known in the art and are not discussed in detail in the present disclosure. Those skilled in the art will appreciate that carbonation technologies may be deployed in various positions within a DLE operation or may not be required at all. The systems, devices, and / or methods of the present disclosure may improve carbonation technologies by, for example, detecting lithium and / or detecting bicarbonate concentration before and / or after the carbonation technology 712. Detecting carbonate concentration after the carbonation technology 712 may facilitate quantification of the chemical equilibrium associated with carbonation and may aid in determining the amount of precipitating agent required.

[0099] In DLE, finishing technologies are generally employed to filter, rinse, recrystallize, and / or otherwise purify lithium carbonate, lithium chloride, or lithium hydroxide. Finishing technologies, such as the finishing technologies 714 depicted in Fig. 13, are generally known in the art and are not discussed in detail in the present disclosure. Those skilled in the art will appreciate that finishing technologies may be deployed in various positions within a DLE operation or may not be required at all. The systems, devices, and / or methods of the present disclosure may improve finishing technologies by, for example, detecting lithium and / or detecting elemental contaminant concentration before finishing technology 712.EXAMPLES & EXPERIMENTATION

[0100] The following description reports work conducted to study and investigate certain aspects of the present techniques. It is appreciated that the LIBS systems, devices, and methods disclosed herein may have a number of features, variations, and applications. As such, the following description is provided to further illustrate some aspects and capabilities of the present techniques, but should not be construed as in any way limiting their scope.

[0101] In an archetypal system and device configuration used for the present experiments, a pump was used to create a stream of a fluid sample through a capillary tube. The fluid sample exited from the outlet of the capillary tube as a free-falling, open-stream flow along a sample path flow within a flow cell chamber of a flow cell. A flow of curtain gas was used to deflect the liquid splashes away from the excitation and emission light paths, so as to prevent or at least mitigate splashing and contamination of the excitation and collection optics. The flow of curtain gas was generated inside a curtain gas channel by blowing compressed air via anair nozzle. The curtain gas channel was formed within a wall of the flow cell and positioned to intersect the input and output optical ports. Laser pulses (pulse repetition rate: 1-20 Hz) were focused by excitation optics onto the streaming sample at a point near the outlet of the capillary tube. Fluid splashing due to shock wave generation on the surface of the streaming sample was reduced by application of the curtain gas. The laser pulses were allowed to enter the flow cell chamber via an input optical port of the flow cell. The laser pulses energized the fluid sample to form a plasma within the flow cell chamber. Elements within the sample were energized to an excited state, and emitted LIBS emission light during relaxation back to a ground state. The laser-induced emission exited the flow cell chamber along an emission light path passing through an output optical port of the flow cell. The LIBS emission light was collected by collection optics, which directed the LIBS emission light to a multichannel spectral detection device (e.g., a four-channel spectral detection device) via fiber optics (e.g., a l-to-4 fiber-optic bundle). Depending on the concentration of the analytes, the data acquisition time was varied from milliseconds to seconds. Several scans were usually averaged to increase the signal-to-noise ratio of the spectra. In some of the present experiments, a delay generator was used while collecting spectra to set a delay between the laser shots and the data collection.

[0102] A representative LIBS spectrum of DLE brine is depicted in Fig. 14. The peaks at 610 nm and 671 nm correspond to Li (4040 ppm); the peaks 589 nm and 590 nm correspond to Na (69,300 ppm); the peaks at 279 nm, 280 nm, and 285 nm correspond to Mg (10,200 ppm); the peaks at 393 nm, 396 nm, and 422 nm correspond to Ca (28,300 ppm); and the broad peak at 657 nm corresponds to H. The LIBS spectrum shown in Fig. 14 is the average of 50 scans, with a per-scan acquisition time of 200 ms. The analysis displays acceptable resolution of elements of interest in DLE operations, and easily accommodates a wide range of elemental concentrations without impact to the data quality. Sample analysis averaging is consistent with a potential on-line analysis of DLE operational fluid streams during constant production. Such an analysis would allow for rapid, automated assessment of both current, real-time process conditions as well as process trends (e.g., monitoring for calcium, magnesium, or other elemental impurity content).

[0103] Air curtain performance was assessed through parallel multi-timepoint analyses. By employing standardized conditions and modifying only the curtain air flow, repeated analysis of a sample stream was carried out to demonstrate the impact of the application of a curtain gas. Two separate experiments were performed. In the first iteration, the sample analysis was executed using standardized conditions, including nominal curtain air gas flow, and performing iterative analyses of a lithium-containing solution at 0 min, 2 min, 5 min, and 10 min. Fig. 15 displays a consistent signal intensity across all timepoints.

[0104] A second experimental iteration was executed using standardized conditions and zero curtain gas flow. Visible splashing was noted immediately upon laser contact with the sample fluid, causing an increasing accumulation of droplets on the laser components and collection optics. Within two minutes, the lithium signal was reduced to approximately half of the nominal intensity that had been achieved with use of the air curtain. At the end of the analysis a final signal intensity of approximately 30% (relative to incident intensity) was noted, as shown in Fig. 16. Consistent application of the air curtain is shown to be necessary for reproducible sample analyses, for low concentration elemental analytes, and must be employed for proper quantitative analysis.

[0105] I n the present disclosure, similar features in the drawings have been given similar reference numerals. To avoid cluttering certain figures, some elements may not be indicated if they were already identified in a preceding figure. The elements of the drawings are not necessarily depicted to scale since emphasis is placed on clearly illustrating the elements and structures of the present embodiments. Positional descriptors indicating the location and / or orientation of one element with respect to another element are used herein for ease and clarity of description. Unless otherwise indicated, these positional descriptors should be taken in the context of the figures and should not be considered limiting. In particular, positional descriptors are intended to encompass different orientations in the use or operation of the present embodiments, in addition to the orientations exemplified in the figures. Furthermore, when a first element is referred to as being "on", "above", "below", "over", or "under" a second element, the first element can be either directly or indirectly on, above, below, over, or under the second element, respectively, such that one or multiple intervening elements may be disposed between the first element and the second element.

[0106] The terms "a", "an", and "one" are defined herein to mean "at least one", that is, these terms do not exclude a plural number of elements, unless stated otherwise.

[0107] The term "or" is defined herein to mean "and / or", unless stated otherwise.

[0108] Terms such as "substantially", "generally", and "about", which modify a value, condition, or characteristic of a feature of an exemplary embodiment, should be understood to mean that the value, condition, or characteristic is defined within tolerances that are acceptable for the proper operation of this exemplary embodiment for its intended application and / or that fall within an acceptable range of experimental error. In particular, the term "about" generally refers to a range of numbers that one skilled in the art would consider equivalent to the stated value (e.g., having the same or an equivalent function or result). In some instances, the term "about" means a variation of ±10% of the stated value. It is noted that all numeric values used herein are assumed to be modified by the term "about", unless stated otherwise. Theterm "between" is used herein to refer to a range of numbers or values defined by endpoints is intended to include both endpoints, unless stated otherwise.

[0109] The term "based on" as used herein is intended to mean "based at least in part on", whether directly or indirectly, and to encompass both "based solely on" and "based partly on". In particular, the term "based on" may also be understood as meaning "from", "depending on", "representative of", "indicative of", "associated with", "relating to", and the like.

[0110] The terms "match", "matching", and "matched" refer herein to a condition in which two elements are either the same or within some predetermined tolerance of each other. That is, these terms are meant to encompass not only "exactly" or "identically" matching the two elements, but also "substantially", "approximately", or "sufficiently" matching the two elements, as well as providing a higher or best match among a plurality of matching possibilities.

[0111] The terms "connected" and "coupled", and derivatives and variants thereof, refer herein to any connection or coupling, either direct or indirect, between two or more elements, unless stated otherwise. For example, the connection or coupling between the elements may be mechanical, optical, electrical, magnetic, thermal, chemical, logical, fluidic, operational, or any combination thereof.

[0112] The term "concurrently" refers herein to two or more processes that occur during coincident or overlapping time periods. The term "concurrently" does not necessarily imply complete synchronicity and encompasses various scenarios including time-coincident or simultaneous occurrence of two processes; occurrence of a first process that both begins and ends during the duration of a second process; and occurrence of a first process that begins during the duration of a second process, but ends after completion of the second process.

[0113] In the present disclosure, the term "measured" when referring to a quantity or parameter is intended to mean that the quantity or parameter can be measured either directly or indirectly. In the case of indirect measurement, the quantity or parameter can be derived, retrieved, inferred or otherwise determined from directly measured data.

[0114] The terms "light" and "optical", and variants and derivatives thereof, refer herein to radiation in any appropriate region of the electromagnetic spectrum. These terms are not limited to visible light, but may also include invisible regions of the electromagnetic spectrum including, without limitation, the ultraviolet and infrared spectral bands. For example, in some embodiments the present techniques can be implemented with optical signals having an optical signal bandwidth lying within a wavelength band ranging from about 200 nm(in the ultraviolet) to about 2000 nm (in the near-infrared). Those skilled in the art will understand, however, that this wavelength range is provided for illustrative purposes only and that the present techniques may operate beyond this range. It is noted that spectral variables such as wavelength, frequency, wavenumber, and energy may be used interchangeably herein, since converting between these different quantities is straightforward and well known in the art.

[0115] Numerous modifications could be made to the embodiments described above without departing from the scope of the appended claims.

Claims

CLAIMS1. A system for laser-induced breakdown spectroscopy (LIBS) analysis of a fluid sample, the system comprising: a laser source configured to generate excitation laser light along an excitation light path; a flow cell comprising: a flow cell body enclosing a flow cell chamber; a sample injection port configured to supply a flow of the fluid sample along a sample flow path within the flow cell chamber; an input optical port configured to allow the excitation laser light to enter the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma; and an output optical port configured to allow LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path; a spectral detection device configured to detect the LIBS emission light exiting the flow cell chamber; measurement optics disposed along the excitation light path and the emission light path; and a curtain gas channel configured to convey a flow of curtain gas therealong to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path to impede the sample ejections from reaching the measurement optics.

2. The system of claim 1, wherein the laser source is configured to generate the excitation laser light with an excitation wavelength ranging from about 200 nm to about 2000 nm.

3. The system of claim 1 or 2, wherein the measurement optics are positioned outside the flow cell chamber.

4. The system of any one of claims 1 to 3, wherein the measurement optics comprises one or more lenses, and / or one or more mirrors, and / or one or more spectral filters.

5. The system of any one of claims 1 to 4, wherein the sample flow path is substantially perpendicular to the excitation light path and the emission light path.

6. The system of any one of claims 1 to 5, wherein the sample injection port is configured to supply the fluid sample as a mist.

7. The system of any one of claims 1 to 6, wherein the sample injection port comprises a nozzle.

8. The system of any one of claims 1 to 5, wherein the sample injection port is configured to supply the fluid sample as an open-stream flow.

9. The system of any one of claims 1 to 8, wherein the sample injection port is configured to supply the fluid sample as a laminar flow.

10. The system of any one of claims 1 to 9, wherein the sample injection port is configured to supply the fluid sample to flow substantially along the direction of gravity.

11. The system of any one of claims 1 to 9, wherein the sample injection port is configured to supply the fluid sample to flow substantially transverse to the direction of gravity.

12. The system of any one of claims 1 to 11, wherein the sample injection port comprises a capillary tube.

13. The system of any one of claims 1 to 12, wherein the flow cell body comprises at least one opening formed therethrough that defines the input optical port and the output optical port.

14. The system of claim 13, wherein the at least one opening comprises distinct first and second openings, the first opening corresponding to the input optical port and the second opening corresponding to the output optical port.

15. The system of claim 13, wherein the at least one opening comprises a single opening.

16. The system of any one of claims 13to 15, wherein the flow cell body comprises a cavity formed therein that defines the curtain gas channel, and wherein the cavity overlaps and extends across the at least one opening.

17. The system of any one of claims 1 to 16, wherein the curtain gas channel comprises a single curtain gas flow path that establishes a gas curtain across both the input optical port and the output optical port.

18. The system of any one of claims 1 to 16, wherein the curtain gas channel comprises distinct first and second curtain gas flow paths, the first curtain gas flow path establishing a first gas curtain across the input optical port and the second curtain gas flow path establishing a second gas curtain across the output optical port.

19. The system of any one of claims 1 to 18, wherein the flow of curtain gas along the curtain gas channel is substantially in a same direction as the flow of the fluid sample along the sample flow path.

20. The system of any one of claims 1 to 18, wherein the flow of curtain gas along the curtain gas channel is substantially in an opposite direction to the flow of the fluid sample along the sample flow path.

21. The system of any one of claims 1 to 20, wherein the flow of curtain gas along the curtain gas channel is substantially along the direction of gravity.

22. The system of any one of claims 1 to 20, wherein the flow of curtain gas along the curtain gas channel is substantially against the direction of gravity.

23. The system of any one of claims 1 to 22, wherein the curtain gas comprises air, nitrogen, or argon.

24. The system of any one of claims 1 to 23, further comprising a curtain gas supply unit configured to supply the curtain gas into the curtain gas channel.

25. The system of claim 24, wherein the curtain gas supply unit is configured to supply the curtain gas into the curtain gas channel in a blow mode.

26. The system of claim 24, wherein the curtain gas supply unit is configured to supply the curtain gas into the curtain gas channel in a suction mode.

27. The system of any one of claims 24 to 26, wherein the curtain gas supply unit comprises an injection nozzle configured to control the flow of the curtain gas injected into the curtain gas channel.

28. The system of any one of claims 1 to 27, wherein the flow cell body comprises a base, a cover, and a sidewall extending along a flow cell axis between the base and the cover.

29. The system of claim 28, wherein the flow cell body has a substantially cylindrical configuration about the flow cell axis.

30. The system of claim 28 or 29, wherein the sample flow path is substantially parallel to the flow cell axis.

31. The system of claim 28 or 29, wherein the sample flow path is tilted relative to the flow cell axis in a tilt direction which, in a plane perpendicular to the flow cell axis, points away from the input optical port and / or the output optical port.

32. The system of any one of claims 28 to 31, wherein the sample injection port extends within the flow cell chamber via an opening formed through the cover and is configured to supply the fluid sample to flow along the sample flow path toward the base.

33. The system of any one of claims 28 to 32, wherein the input optical port and the output optical port are formed through the sidewall.

34. The system of any one of claims 28 to 33, wherein an angular separation between the input optical port and the output optical port in a plane perpendicular to the flow cell axis ranges from about 1° to about 20°.

35. The system of any one of claims 28 to 34, wherein the curtain gas channel extends within the sidewall between a curtain gas inlet and a curtain gas outlet, the curtain gas inlet is arranged at one of the base and the cover, and the curtain gas outlet is arranged at the other one of the base and the cover.

36. The system of claim 35, wherein the curtain gas channel has an annular-sector-shaped cross-section in a plane perpendicular to the flow of curtain gas.

37. The system of any one of claims 1 to 36, further comprising a sample collector configured to collect the fluid sample after interaction of the fluid sample with the excitation laser light.

38. The system of claim 37, further comprising a sample discharge port configured to remove the fluid sample from the sample collector.

39. The system of any one of claims 1 to 38, further comprising an ejection collector configured to collect the sample ejections conveyed along and discharged from the curtain gas channel.

40. The system of any one of claims 1 to 39, wherein the spectral detection unit comprises a spectrometer and an optical detector.

41. The system of any one of claims 1 to 40, further comprising a computer device operatively coupled to the spectral detection device, wherein the computer device comprises a processor and a non-transitory computer readable storage medium having stored thereon computer readable instructions that, when executed by the processor, cause the processor to analyze the LIBS emission light detected by the spectral detection device and derive therefrom analyte information about a presence or absence of one or more constituent elements in the fluid sample.

42. The system of claim 41, wherein the analyte information further comprises a concentration of the one or more constituent elements in the fluid sample.

43. The system of claim 41 or 2 wherein the one or more constituent elements in the fluid sample comprise Li, or Na, or Ca, or Mg, or Al, or K, or S, or B, or P, or Si, or Pb, or As, or Hg, or Cd, or any combination thereof.

44. The system of any one of claims 1 to 43, wherein the sample fluid is an aqueous sample.

45. The system of any one of claims 1 to 44, wherein the sample fluid is a lithium-containing brine.

46. The system of any one of claims 1 to 44, wherein the sample fluid is a plant nutrient solution.

47. The system of any one of claims 1 to 46, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid stream flowing within a conduit.

48. The system of any one of claims 1 to 46, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid contained in a fluid reservoir.

49. The system of any one of claims 1 to 48, wherein the the sample injection port is configured with a filtration apparatus.

50. The system of any one of claims 1 to 49, wherein the curtain gas channel is configured to convey the flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.

51. A flow cell device for use in laser-induced breakdown spectroscopy (LIBS) analysis of a fluid sample, the flow cell device comprising: a flow cell comprising: a flow cell body enclosing a flow cell chamber; a sample injection port configured to supply a flow of the fluid sample along a sample flow path within the flow cell chamber; an input optical port configured to allow excitation laser light from a laser source to enter the flow cell chamber along an excitation light path intersecting the sample flow path and energize the fluid sample to form a laser-induced plasma; and an output optical port configured to allow LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path leading to a spectral detection device; and a curtain gas channel configured to convey a flow of curtain gas therealong to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path.

52. The flow cell device of claim 51, wherein the sample injection port is configured to supply the fluid sample as an open-stream flow.

53. The flow cell device of claim 51 or 52, wherein the sample injection port is configured to supply the fluid sample as a laminar flow.

54. The flow cell device of claim 51, wherein the sample injection port is configured to supply the fluid sample as a mist.

55. The flow cell device of any one of claims 51 to 53, wherein the sample injection port comprises a nozzle.

56. The flow cell device of any one of claims 51 to 55, wherein the sample injection port is configured to supply the fluid sample to flow substantially along the direction of gravity.

57. The flow cell device of any one of claims 51 to 55, wherein the sample injection port is configured to supply the fluid sample to flow substantially transverse to the direction of gravity.

58. The flow cell device of any one of claims 51 to 57, wherein the sample injection port comprises a capillary tube.

59. The flow cell device of any one of claims 51 to 58, wherein the flow cell body comprises at least one opening formed therethrough that defines the input optical port and the output optical port.

60. The flow cell device of claim 59, wherein the flow cell body comprises a cavity formed therein that defines the curtain gas channel, and wherein the cavity overlaps and extends across the at least one opening.

61. The flow cell device of any one of claims 51 to 60, wherein the curtain gas channel comprises a single curtain gas flow path that intersects both the input optical port and the output optical port.

62. The flow cell device of any one of claims 51 to 60, wherein the curtain gas channel comprises distinct first and second curtain gas flow paths, the first curtain gas flow path establishing a first gas curtain across the input optical port and the second curtain gas flow path establishing a second gas curtain across the output optical port63. The flow cell device of any one of claims 51 to 62, wherein the flow of curtain gas along the curtain gas channel is substantially along the direction of gravity.

64. The flow cell device of any one of claims 51 to 62, wherein the flow of curtain gas along the curtain gas channel is substantially against the direction of gravity.

65. The flow cell device of any one of claims 51 to 64, wherein the curtain gas comprises air, nitrogen, or argon.

66. The system of any one of claims 51 to 65, further comprising a curtain gas supply unit configured to supply the curtain gas into the curtain gas channel.

67. The flow cell device of claim 66, wherein the curtain gas supply unit comprises an injection nozzle configured to control the flow of the curtain gas injected into the curtain gas channel.

68. The flow cell device of any one of claims 51 to 67, wherein the flow cell body comprises a base, a cover, and a sidewall extending along a flow cell axis between the base and the cover.

69. The flow cell device of claim 68, wherein the flow cell body has a substantially cylindrical configuration about the flow cell axis.

70. The flow cell device of claim 68 or 69, wherein the sample flow path is substantially parallel to the flow cell axis.

71. The flow cell device of claim 68 or 69, wherein the sample flow path is tilted relative to the flow cell axis in a tilt direction which, in a plane perpendicular to the flow cell axis, points away from the input optical port and / or the output optical port.

72. The flow cell device of any one of claims 68 to 71, wherein the sample injection port extends within the flow cell chamber via an opening formed through the cover and is configured to supply the fluid sample to flow along the sample flow path toward the base.

73. The flow cell device of any one of claims 68 to 72, wherein the input optical port and the output optical port are formed through the sidewall.

74. The flow cell device of any one of claims 68 to 73, wherein an angular separation between the input optical port and the output optical port in a plane perpendicular to the flow cell axis ranges from about 1° to about 20°.

75. The flow cell device of any one of claims 51 to 74, further comprising a sample collector configured to collect the fluid sample after interaction of the fluid sample with the excitation laser light.

76. The flow cell device of claim 75, further comprising a sample discharge port configured to remove the fluid sample from the sample collector.

77. The flow cell device of any one of claims 51 to 76, further comprising an ejection collector configured to collect the sample ejections conveyed along and discharged from the curtain gas channel.

78. The flow cell device of any one of claims 51 to 77, wherein the sample fluid is an aqueous sample.

79. The flow cell device of any one of claims 51 to 78, wherein the sample fluid is a lithium-containing brine.

80. The flow cell device of any one of claims 51 to 78, wherein the sample fluid is a plant nutrient solution.

81. The flow cell device of any one of claims 51 to 80, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid stream flowing within a conduit.

82. The flow cell device of any one of claims 51 to 80, wherein the sample injection port is configured to take in the fluid sample therethrough from a fluid contained in a fluid reservoir.

83. The flow cell device of any one of claims 51 to 82, wherein the curtain gas channel is configured to convey the flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.

84. A method of performing laser-induced breakdown spectroscopy (LIBS) of a fluid sample, the method comprising: supplying a flow of the fluid sample along a sample flow path within a flow cell chamber; generating excitation laser light along an excitation light path; introducing the excitation laser light into the flow cell chamber along the excitation light path to intersect the sample flow path and energize the fluid sample to form a laser-induced plasma; allowing LIBS emission light emitted from the laser-induced plasma to exit the flow cell chamber along an emission light path; detecting the LIBS emission light; and providing a flow of curtain gas to deflect sample ejections emanating from the laser-induced plasma away from the excitation light path and / or the emission light path.

85. The method of claim 84, wherein the step of generating the excitation laser light comprises selecting an excitation wavelength of the excitation laser light in a range from about 200 nm to about 2000 nm.

86. The method of claim 84 or 85, wherein deflecting the sample ejections comprises impeding the sample ejections from exiting the flow cell chamber and reaching measurement optics disposed along the excitation light path and the emission light path.

87. The method of any one of claims 84 to 86, wherein the sample flow path is substantially perpendicular to the excitation light path and the emission light path.

88. The method of any one of claims 84 to 87, wherein the supplying the flow of the fluid sample comprises supplying the fluid sample as an open-stream flow.

89. The method of any one of claims 84 to 88, wherein the supplying the flow of the fluid sample comprises supplying the fluid sample as a laminar flow.

90. The method of any one of claims 84 to 89, wherein supplying the flow of the fluid sample comprises supplying the fluid sample as a mist.

91. The method of any one of claims 84 to 90, wherein providing the flow of curtain gas comprises supplying the flow of curtain gas along a curtain gas channel that intersects the excitation light path and the emission light path.

92. The method of claim 91, further comprising: enclosing the flow cell chamber within a flow cell body; forming at least one opening through the flow cell body to define an input optical port configured to allow the excitation laser light to enter the flow cell chamber and allow the LIBS emission light to exit the flow cell chamber; and forming a cavity inside the flow cell body to define the curtain gas channel, wherein the cavity overlaps and extends the at least one opening.

93. The method of claim 92, further comprising tilting the sample flow path in a tilt direction that points away from the input optical port and / or the output optical port.

94. The method of any one of claims 84 to 92, wherein supplying the flow of the fluid sample comprises supplying the fluid sample substantially along the direction of gravity.

95. The method of any one of claims 84 to 94, further comprising collecting the fluid sample after interaction of the fluid sample with the excitation laser light.

96. The method of any one of claims 84 to 95, further comprising collecting the sample ejections conveyed by the flow of curtain gas.

97. The method of any one of claims 84 to 96, further comprising analyzing the detected LIBS emission light and deriving therefrom analyte information about a presence or absence of one or more constituent elements in the fluid sample.

98. The method of claim 97 , wherein the analyte information further comprises a concentration of the one or more constituent elements in the fluid sample.

99. The method of any one of claims 84 to 98, wherein the sample fluid is an aqueous sample.

100. The method of any one of claims 84 to 99, wherein the sample fluid is a lithium-containing brine.

101. The method of any one of claims 84 to 99, wherein the sample fluid is a plant nutrient solution.

102. The method of any one of claims 84 to 101, wherein supplying the flow of the fluid sample comprises: drawing off the fluid sample from a fluid stream flowing within a conduit; and introducing the drawn-off fluid sample into the sample flow path.

103. The method of any one of claims 84 to 102, wherein supplying the flow of the fluid sample along the sample flow path comprises: drawing off the fluid sample from a fluid contained in a fluid reservoir; and introducing the drawn-off fluid sample into the sample flow path.

104. The method of any one of claims 84 to 103, wherein the flow of curtain gas is provided to deflect sample ejections emanating from the laser-induced plasma away from both the excitation light path and the emission light path.

105. The method of any one of claims 84 to 104, wherein the LIBS analysis is performed in concert with additional analytical methodology.

106. The method of claim 105, wherein the LIBS analysis is performed (i) prior to a secondary analysis, (ii) after a secondary analysis, or (iii) concurrently with a secondary analysis.

107. The method of claim 105, wherein the LIBS analysis and the secondary analysis are performed on the same fluid sample.

108. The method of claim 106 or 107 wherein the secondary analysis is performed using some or all of the spectrophotometric components of the LIBS system.

109. The method of claim 106 or 108, wherein the LIBS and the secondary analysis are performed on separate fluid samples.

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