Plasma elemental analysis method and device

Abstract

An analytical method and apparatus using laser ablation and plasma ion sources that does not require a solid standard is provided. [Solution] A plasma elemental analysis method and apparatus finely atomize a solution standard using a nebulizer and introduce the solution into a plasma, create calibration curve data for elements contained in the solution standard, finely atomize a solid sample to be measured by laser ablation, introduce the sample into the plasma together with an auxiliary liquid from the nebulizer and ionize the sample to create elemental analysis data, obtain the concentration of the measured element in the solid sample from the elemental analysis data and the calibration curve data, and correct and quantify the concentration of the measured element.

Description

[Technical field]

[0001] The present invention relates to a plasma elemental analysis method and an analytical device for quantifying the constituent elements of a solid sample, in particular to elemental analysis using a combination of laser ablation (LA) and a plasma ion source (ICP), and more particularly to inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma optical emission spectrometry (ICP-OES) using laser ablation. [Background technology]

[0002] As an analytical method using a plasma ion source, for example, ICP-MS, which is a mass spectrometry method, is useful for analyzing inorganic elements, especially trace amounts of metals, and is widely used in many fields including the semiconductor, geology, and environmental industries. ICP-MS allows for substantially simultaneous multi-element analysis of most elements in the periodic table, and allows for the quantification of element concentrations at an excellent sensitivity level of parts per billion (ppb) or parts per trillion (ppt).

[0003] Similarly, ICP optical emission spectrometry, which is an analytical method that uses a plasma ion source, is suitable for rapid analysis of a large number of samples with relatively high elemental concentrations. The element-specific spectra emitted when introduced into the plasma are broken down using a grating, and a large number of elements can be rapidly measured from the emission intensity.

[0004] Analytical methods using plasma ion sources are also useful for the analysis of solid samples, and when measuring solid samples, pretreatment such as acid decomposition can be performed before introducing the solution. However, acid decomposition is time-consuming and dangerous, and there is a possibility that the sample may be contaminated by acid. Furthermore, since the entire solid sample is decomposed with acid, it is not suitable for local analysis. In contrast, when laser ablation (LA) is used as a sample introduction device, it is possible to directly introduce solid samples, which has the advantage of being suitable for local analysis. From this perspective, LA-ICP-MS and LA-ICP-OES have traditionally been used in fields such as geoscience.

[0005] For example, Patent Document 1 describes a technology that uses a LA-ICP-MS device to measure elements such as carbon that were previously difficult to measure, and corrects the measurement results of a measurement sample that contains a large amount of that element, thereby enabling accurate quantitative analysis of the measured elements in the measurement sample.

[0006] Furthermore, Patent Document 2 describes a technique for quantitative analysis without using a solid standard sample, based on the ICP signal intensity due to laser ablation of a solid sample in the LA section and the ICP signal intensity of a sample obtained by heating and vaporizing a standard liquid sample containing known amounts of elements contained in the solid sample using the ETV method. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-347473 A [Patent Document 2] JP 2018-136190 A Summary of the Invention [Problem to be solved by the invention]

[0008] Using sample introduction by LA, not only can solid samples be rapidly analyzed by ICP-MS or ICP-OES without pretreatment with acid, but also local analysis and imaging analysis of solid samples become possible. Laser ablation is typically performed by placing a sample in a cell with a window through which the laser light can pass and irradiating it with a laser while a carrier gas is flowing through it. The laser is focused on the sample surface and irradiated, and the sample particles (aerosol) generated by the irradiation are introduced into the plasma, ionized, and analyzed for elements.

[0009] In the past, when quantitative analysis of solids was performed using laser ablation, glass standard materials, steel standard materials, etc. were used as standard materials. For example, in Patent Document 1, it was necessary to secure a standard material that contains the same composition as the sample to be measured and the target element at a known concentration. However, such standard materials are limited in the element types and concentrations they contain, and it is difficult to use them if they do not match the target of analysis. In addition, if the target of analysis and the matrix are different, there will be a difference in the ionization efficiency of the elements, resulting in different signal intensities, and it may not be possible to accurately measure the element concentration in the sample.

[0010] Therefore, various steel materials and SiO 2 Quantitative analysis is possible for materials for which standard samples can be prepared manually, such as the main component glass material, but accurate quantitative analysis is difficult when it is difficult to prepare standard samples of materials with similar chemical compositions, and the scope of application is limited. Patent Document 2 proposes quantitative analysis using LA-ICP-MS without using solid standard samples, but it is necessary to first identify the elements contained in the solid sample and then prepare matrix-matched liquid standard samples with known element concentrations.

[0011] Therefore, it is desirable to provide a method and apparatus for performing analytical measurements using laser ablation and a plasma ion source, which can quantitatively analyze solid samples in a simple manner without requiring solid standard samples. [Means for solving the problem]

[0012] According to one embodiment of the present invention, there is provided a plasma elemental analysis method for quantifying constituent elements of a solid sample. In this method, a solution standard is atomized, for example, by a nebulizer, introduced into a plasma, excited and / or ionized, and subjected to spectroscopic or mass spectrometry, and calibration curve data is created for the elements contained in the solution standard. The solid sample to be measured is placed in a sealed cell, atomized by laser ablation, introduced into the plasma together with an auxiliary liquid atomized, for example, by a nebulizer, by a gas supplied to the cell, excited and / or ionized, and subjected to mass spectrometry, and elemental analysis data is created for the elements contained in the solid sample.

[0013] In one embodiment, the auxiliary liquid is matrix-matched to the solution standard. The calibration curve data and the elemental analysis data may be generated in any order. The concentration of the measured element in the solid sample is obtained from the elemental analysis data and the calibration curve data, and the concentration of the measured element is corrected to perform quantification.

[0014] A solid sample may contain a measurement element that is not contained in the solution standard. In one embodiment of the present invention, calibration curve data for such a measurement element may be created based on the semi-quantitative coefficient of the measurement element and the calibration curve data of the measurement element contained in the solution standard. The semi-quantitative coefficient can be created for all elements by measuring a standard solution containing a plurality of elements with known concentrations, and represents the relative sensitivity of each element. Calibration curve data for a measurement element that is not contained in the solution standard can be created based on the semi-quantitative coefficient obtained in advance and the calibration curve data of a measurement sample contained in the solution standard.

[0015] According to another embodiment of the present invention, there is provided a plasma elemental analysis device for quantifying the constituent elements of a solid sample. This device includes an analysis section, such as a spectroscopic analysis section or a mass analysis section, that performs elemental analysis by exciting and / or ionizing a sample introduced from a sample introduction section with plasma. The sample introduction section can include a sealed cell that atomizes the solid sample by laser ablation and introduces the atomized solid sample into the plasma, and a nebulizer that individually atomizes a solution standard or an auxiliary liquid and introduces the atomized solid sample into the plasma.

[0016] According to a further embodiment of the present invention, the analytical device may perform the above-described analytical method according to the present invention. That is, the analytical device may generate calibration curve data in an analysis section for an element contained in a solution standard that has been atomized by a nebulizer and introduced into plasma. When a measurement element that is not contained in the solution standard is contained in a solid sample, the analytical device may optionally generate calibration curve data for such a measurement element based on a semi-quantitative coefficient of the measurement element and the calibration curve data of the measurement element contained in the solution standard.

[0017] The solid sample is atomized by laser ablation, then merges with the auxiliary liquid atomized by the nebulizer, is introduced into the plasma, and is excited and / or ionized to generate elemental analysis data. The calibration curve data and the elemental analysis data can be generated in either order. The analyzer can further obtain the concentration of the measured element in the solid sample from the elemental analysis data and the calibration curve data in the analysis section, and can correct and quantify the concentration of the measured element.

[0018] The concentration of the measured element may be corrected by standardizing the total concentration of the measured element obtained by the analysis device, for example, the normalization is 100%. That is, when the concentrations of the measured elements obtained from the calibration curve data and the elemental analysis data are added, the result is usually different from 100% by mass, but in this case, by standardizing the total to 100%, the composition ratio of the constituent elements of the solid sample can be more appropriately displayed.

[0019] However, if the composition of the main components of the solid sample is known, the analysis unit may normalize to the amount of something other than the main components, for example, 30%, 50%, or 70%. For example, if the sum of the concentrations of the measured elements is a known N%, normalization may be N% normalization. Also, if the measured element is a compound with other elements, normalization may be performed by multiplying the obtained concentration of the measured element by a coefficient calculated from the known composition (chemical formula) of the compound.

[0020] The auxiliary liquid may be matrix-matched to the solution standard, for example, dilute nitric acid of the same concentration, such as 1% by mass or 3% by mass. As described above, the auxiliary liquid is aerosolized and introduced into the plasma together with the fine particles of the laser-ablated solid sample. In other words, the fine particles of the solid sample are introduced into the plasma in a wet state. It has been found that the sensitivity of elemental analysis is several times higher when the auxiliary liquid is used in the plasma (wet plasma).

[0021] The auxiliary liquid atomized by the nebulizer may be mixed with the solid sample atomized by laser ablation in the spray chamber, which has the effect of causing the solid sample with large particle size to fall off. The mixing in the spray chamber may be performed at the rear of the spray chamber. Effect of the Invention

[0022] According to the present invention, there is provided an analytical method capable of performing plasma elemental analysis of the types and concentrations of elements in a solid sample with high accuracy without requiring a solid standard sample or a matrix-matched standard substance, and Device In particular, analytical methods and apparatus using laser ablation and plasma ion sources, such as LA-ICP-MS or LA-ICP-OES methods and apparatus, are provided. [Brief description of the drawings]

[0023] [Figure 1]FIG. 1 is a schematic diagram of a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) apparatus according to one exemplary embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a laser ablation (LA) unit according to one exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] <Quantitative analysis device> 1, which is a quantitative analysis device according to one exemplary embodiment of the present invention, converts a solid sample to be measured into fine particles, i.e., aerosol, by laser ablation, and introduces the finely divided sample into an inductively coupled plasma (ICP) for excitation and / or ionization. In one embodiment of the present invention, an LA section 10 that performs laser ablation on a solid sample placed in a chamber of a cell, and a liquid introduction section 12 including a nebulizer are connected to a sample introduction section 15. The LA section has a sealed structure, and a carrier gas is introduced into the chamber as described below, and is connected to an ICP-MS device, more specifically, an ionization section 20 of the ICP-MS device.

[0025] As shown in FIG. 2, the LA unit 10 has a sample cell 102 in which a solid sample 101 to be analyzed is placed in a chamber, and is provided with a laser irradiation mechanism mainly including a laser oscillator 103 and galvanometer mirrors 104 and 105 in the X-axis and Y-axis directions. The sample cell 102 is placed on a stage 106, and the stage 106 can be leveled by correcting the tilt three-dimensionally using, for example, a two-axis gonio mechanism (not shown). After placing the sample cell 102 on the stage 106, the ablation position can be set while observing the sample surface with, for example, a coaxial camera (not shown) with an AF function. Such setting may be performed, for example, from a dedicated tablet terminal.

[0026] In this LA unit 10, a laser beam emitted from a laser oscillator 103 at a predetermined wavelength is reflected by galvanometer mirrors 104 and 105 in the X-axis and Y-axis directions, passes through a focusing fθ lens 107, and is irradiated onto the surface of a solid sample 101 to be analyzed. As an ablation laser, for example, a 213 nm or 266 nm Nd:YAG laser or a 193 nm excimer laser can be used, but a laser with a femtosecond (fs) pulse width is preferably used. By using a short-wavelength laser, the sample aerosol can be made smaller, ionization in the plasma can be promoted to suppress elemental fractionation, and the increase in matrix effect and spike-like signals due to a decrease in plasma temperature can be suppressed.

[0027] In addition, by using an ultrashort pulse laser such as a femtosecond laser, it is possible to analyze samples with high thermal conductivity without heating or melting them. In particular, for materials with low melting points and thermal conductivity such as metals and alloys, it is possible to obtain particles that more accurately reflect the elemental composition of the bulk material.

[0028] To the sample cell 102, an inlet pipe 108 for introducing a carrier gas composed of a rare gas such as helium or argon, and an outlet pipe 109 for leading the gas to the outside of the sample cell 102 are connected. The outlet pipe 109 is connected to the ionization section 20 of the ICP-MS device at the sample introduction section 15. Therefore, the carrier gas introduced into the sample cell 102 by the inlet pipe 108 is led to the ionization section 20 through the outlet pipe 109 together with the solid sample 101 vaporized by irradiation with a laser beam.

[0029] In one specific embodiment, an ultrashort pulse (femtosecond) deep ultraviolet laser (FHG: quadruple wave) emitted from a laser oscillator 103 is reflected by galvanometer mirrors 104 and 105 in the X-axis and Y-axis directions, and is focused by an fθ lens 107 to ablate the solid sample 101. The solid sample 101 is instantly heated and vaporized by the ablation, but then re-aggregates (re-condenses) to become fine particles. The fine particles (aerosol) thus generated have a size of several hundred nanometers, and are carried from the outlet tube 109 to the sample introduction section 15 by a carrier gas of helium or argon supplied from the inlet tube 108 to the sample cell 102. Note that argon can be mixed here to increase the transport efficiency to the ionization section 20 (see the arrow in FIG. 2).

[0030] In an exemplary embodiment of the present invention, a vial 151 for introducing a liquid sample is connected to the sample introduction section 15 via a pump 152 and a nebulizer 153. The nebulizer 153 converts the liquid sample into an aerosol and may include a spray chamber 154 for removing large droplets from the aerosolized sample. A sample supply conduit extending from the nebulizer 153 merges with an outlet tube 109 extending from the sample cell 102 of the LA section 10 in the sample introduction section 15 and can be led to the ionization section 20. The fine mist of sample sprayed into the spray chamber 154 is particle-sorted in the chamber, and a portion of it is led to the plasma of the ionization section 20. The remainder may be discharged from a drain.

[0031] Nebulizer 153 can utilize argon or other inert gas from a gas source to aerosolize the liquid sample. This inert gas can be the same gas utilized to form the plasma in ionization section 20. Pump 152 can be a peristaltic pump, a syringe pump, or the like. Vial 151 can include auxiliary liquids such as solution standards or aqueous nitric acid solutions in accordance with embodiments of the present invention, but can also include various tuning fluids, calibration fluids, rinse fluids, and the like. Also, an automated device configured to switch between various vials can be included.

[0032] Microparticles or aerosols generated by laser ablation from the solid sample 101, an aerosol of a solution standard or auxiliary liquid drawn from a vial 151 by a pump 152 and atomized by a nebulizer 153, and / or both are introduced into the ionization section 20 through the sample introduction section 15, where they are decomposed, atomized, and ionized in the plasma as described below, and then analyzed by a mass spectrometer.

[0033] Alternatively, the fine particles or aerosol from the LA unit 10 may be introduced into the spray chamber 154 and mixed with the aerosol introduced from the nebulizer 153. That is, in the sample introduction unit 15, the sample supply conduit extending from the nebulizer 153 and the outlet tube 109 extending from the sample cell 102 of the LA unit 10 may join in the spray chamber 154. In particular, in this case, the two may be configured to be mixed at the rear of the spray chamber 154. These configurations have the advantage that, of the fine particles introduced from the LA unit 10, those with large particle diameters can be discharged from the drain.

[0034] A solid and / or liquid sample is aerosolized by laser ablation or a nebulizer and then introduced into the ionization section 20 from the sample introduction section 15, where elements contained in the sample are decomposed and ionized by high-temperature plasma generated by high-frequency electromagnetic induction in the ionization section 20. The ionization section 20 is usually equipped with a plasma torch that generates plasma, and an interface section 25 that constitutes a differential pumping system including a sampling cone and a skimmer cone is located near the tip of the plasma torch. Ions generated in the ionization section 20 are sampled in the interface section 25 and focused by the ion lens section 30 to form an ion beam, which is then incident on the mass separation section 35, which is typically composed of a quadrupole mass filter, in order to pass only ions of a selected mass-to-charge ratio (m / z).

[0035] The mass separation section 35 is designed to allow only ions of a specific mass-to-charge ratio to pass and reach the detector 42 by applying a voltage consisting of a predetermined DC voltage and a predetermined high-frequency AC voltage superimposed on two of the four parallel rod electrodes constituting the quadrupole mass filter with the same polarity (the polarity of one pair of opposing rod electrodes is opposite to the polarity of the other pair of opposing rod electrodes). The mass resolution can be adjusted by changing the ratio of the DC voltage and the high-frequency AC voltage applied to these rod electrodes. The settings of the mass-to-charge ratio and mass resolution are set by the system control section 60 in response to desired input settings by an operator via, for example, an external computing device 70 of the mass spectrometer. Be good.

[0036] The ion beam is then introduced into a high vacuum chamber having a detector 42 therein. The detector 42 is typically composed of a secondary electron multiplier, and outputs an electric signal corresponding to the number of ions with a predetermined mass-to-charge ratio that arrive per unit time, which are separated in the mass separator 35. The electric signal output from the secondary electron multiplier is sent to a pulse counter 44 and an analog current measuring unit 46, and a pulse count value corresponding to the pulse frequency of the electric signal and an analog current value of the electric signal are measured by the pulse counter 44 and the analog current measuring unit 46, respectively. The detector 42, the pulse counter 44, and the analog current measuring unit 46 constitute the ion measuring unit 40.

[0037] The ion lens in the ion lens section 30 is configured so that a voltage is applied from the ion lens voltage driver 55. The ion lens is composed of a group of electric field type lenses that have the effect of changing the trajectory of ions by utilizing an electric field, and is configured so that the ion transmittance changes accordingly when the voltage applied to the electrodes of the ion lens changes. Therefore, it is possible to increase or decrease the ion transmittance of the ion lens by controlling the ion lens voltage driver 55 using the system control section 60 to appropriately change the voltage applied to the electrodes of the ion lens. During normal measurement, the voltage applied to the ion lens is set to a predetermined voltage that maximizes the transmittance of ions of an isotope of an analyte element whose ion intensity is to be measured.

[0038] 1, and an arithmetic processing unit 65 performs data processing such as converting the measured analog current value into the number of ion counts per second (cps) for each mass-to-charge ratio (m / z). The mass spectrometer can be connected to an external computing device 70 such as a PC (personal computer) via a network or the like to transfer data such as the measured ion intensity (ion count number) to the computing device 70, and can perform arithmetic processing to determine the ion intensity of the isotope ions of the analytical element to be measured, and input / output processing with the user.

[0039] When the analysis is an optical emission spectroscopic analysis such as ICP-OES, as is well known, the elements excited and / or ionized by the plasma are emitted as a spectrum, which is resolved into a line spectrum by a diffraction grating and guided to a detector, where the emission intensity is counted, for example, by a photomultiplier tube.

[0040] <Quantitative analysis method> According to one embodiment of the present invention using the quantitative analysis device as described above, the solution standard is atomized and introduced into the plasma, and calibration curve data for at least any one of the elements contained in the solution standard is created. The calibration curve data may be created for some or all of the elements contained in the solution standard. The calibration curve may be created using at least one concentration of the standard solution for each element. The calibration curve data may be created, for example, by the arithmetic processing unit 65 and / or the computing device 70. As described above, when there is a measured element in the solid sample that is not contained in the solution standard, the calibration curve data may be created using a semi-quantitative coefficient.

[0041] As the solution standard, a standard solution with a large number of mixed elements can be used. Various such standard solutions are commercially available, and nitric acid, hydrochloric acid, sulfuric acid, etc. are used as the matrix. For example, SPEX Corporation of the United States sells standard solutions containing various elements at certified concentration values, and a standard solution containing 35 elements such as XSTC-622 can be used. When creating a calibration curve, the concentration can be appropriately diluted, and more than one type of solution standard can be used.

[0042] In this regard, referring to Fig. 1, the standard solution is diluted with ultrapure water having a resistivity of 18.0 MΩ or more, for example, and placed in a vial 151 at several different element concentrations. The standard solution is introduced into the plasma of the ionization unit 20 through the sample introduction unit 145 from the nebulizer 153 by a pump 152 in contact with the liquid, and mass analysis is performed by ICP-MS, and a calibration curve is created based on the relationship between each concentration and signal intensity. In analytical applications that directly use solid samples, such as LA-ICP-MS, all elements in the sample, including matrix elements, are often measured, so it is preferable to create a calibration curve for as many elements as possible. Therefore, a mixture of appropriate combinations of standard solutions that covers all elements in the sample can be used as a solution standard.

[0043] In the present invention, the internal standard method can also be used. When using the internal standard method, a predetermined concentration of an internal standard element is added to the solution standard when creating a calibration curve, and a predetermined concentration of an internal standard element is added to the auxiliary liquid introduced from the nebulizer when measuring a sample. Not one but multiple internal standard elements can be added, which has the advantage that the matrix effect that affects the mass bias can also be corrected. Correction using the internal standard element may be performed when quantifying the measured element.

[0044] Next, the solid sample to be measured is atomized by laser ablation, optionally introduced into plasma together with an auxiliary liquid, and ionized to generate elemental analysis data. For atomization by laser ablation, as shown in FIG. 2, a solid sample 101 to be analyzed is placed in a sample cell 102 of appropriate size mounted on a stage 106. After positioning, such as leveling, is performed using a coaxial camera (not shown), a laser is irradiated from a laser irradiator 103 via a galvanometer mirror, and the solid sample 101 is atomized. Irradiation can be performed in an appropriate pattern according to the application, such as a line pattern, a raster pattern, or a single point pattern.

[0045] The finely divided solid sample 101 is introduced from the sample cell 102 by a carrier gas such as helium through the sample introduction section 15 into the ionization section 20 of the ICP-MS. At this time, an auxiliary liquid may be simultaneously introduced from the vial 151 by the nebulizer 153. The auxiliary liquid may be the same as the matrix of the solution standard. In one non-limiting example, the auxiliary liquid is dilute nitric acid with a concentration of 1 to 5% by mass. By introducing the laser-ablated fine particle aerosol into the ionization section 20 together with the auxiliary liquid, the detection sensitivity of the ICP-MS can be increased compared to the case where the auxiliary liquid is not used.

[0046] At this time, as described above, the fine particles or aerosol from the LA unit 10 may be introduced into the spray chamber 154 and mixed with the aerosol introduced from the nebulizer 153 inside the spray chamber 154, particularly in the rear part of the spray chamber 154. This makes it possible to discharge, from the drain, fine particles with a large particle size among the fine particles introduced from the LA unit 10.

[0047] The signal intensities of the elements of the solid sample 101 analyzed in this manner are converted into ion counts per second (cps) for each mass-to-charge ratio (m / z) by, for example, the arithmetic processor 65 to obtain elemental analysis data. From this elemental analysis data and the calibration curve data created above, the concentration (content) of the element in the solid sample 101 to be analyzed is obtained. This can be done, for example, by the arithmetic processor 65 and / or the external computing device 70 reading from the calibration curve data the concentration corresponding to the signal intensity of the element in the solid sample to be analyzed, which is indicated by the elemental analysis data.

[0048] In the present invention, the standard addition method can also be used. In this case, when the solution standard is atomized and introduced into the plasma to create calibration curve data for the elements contained in the solution standard, the solid sample to be measured can be atomized by laser ablation and introduced into the plasma together with the solution standard. The concentration of each element can be calculated from the signal intensity difference between the obtained calibration curve data and the elemental analysis data obtained by laser ablating the solid sample to be measured and introducing it into the plasma together with the auxiliary liquid. The obtained concentration of each element can be normalized to 100% to obtain the correct concentration.

[0049] Furthermore, according to one embodiment of the present invention, the concentration of the measured element thus obtained is corrected and normalized. In the LA-ICP-MS, all elements of the solid sample 101 can be measured, and content data for almost all of the component elements constituting the solid sample 101 can be obtained by using the calibration curve data created for many elements as described above. In this way, since almost all of the component elements of the solid sample are measured in the present invention, the total of all measured element concentrations can be corrected to, for example, 100%, which makes it possible to correct the variation in the ablation amount. That is, the amount of laser ablation from the solid sample 101 can vary depending on the material (e.g., steel sample and resin sample) and the surface condition (e.g., flat sample and uneven sample), but in the present invention, by correcting to a relative value relative to the total value of all the concentrations of the measured elements, any difference in ablation efficiency can be automatically corrected and analysis can be simplified.

[0050] According to one embodiment of the present invention, the types of elements contained in the solution standard used to prepare the calibration curve data include at least 70% of the component elements constituting the solid sample, preferably at least 80%, more preferably at least 90%, even more preferably at least 95%, and most preferably 100%. By preparing the calibration curve data for as many component elements as possible of the solid sample, the elements in the solid sample can be quantified with high accuracy after normalization.

[0051] According to one embodiment of the present invention, for samples with known main component compositions, for example samples with 30% or 50% of a given main component element, these main component elements may not be measured, and the total of the measured element concentrations may be normalized and corrected to 70% or 50%. Examples of such cases include compounds with elements that cannot be measured by ICP-MS, such as fluorides (CaF, etc.), nitrides (GaN, etc.), and oxides (CaO, etc.), alloys with known ratios of Al, Co, Ni, etc. cannot be measured for all main components, and some main component concentrations are known, such as when the mass % of C is known by other analytical methods in the analysis of plastics. In the case of CaF, GaN, CaO, etc., Ca and Ga may be measured, and compound correction may be performed based on the known composition (chemical formula), and then 100% normalization correction may be performed.

[0052] When taking a depth profile of a solid sample, if the same range is continuously scanned layer by layer with a laser, each layer cannot be analyzed accurately due to the influence of edges formed in the solid sample by ablation. According to one embodiment of the present invention, the scanning range can be narrowed as the depth increases. That is, the sample introduction unit can eliminate the influence of the scanning range edges on the quantitative analysis of the depth of the solid sample by controlling the laser optical system so as to narrow the scanning range for each set number of laser beam scans during laser ablation.

[0053] As another form of control, the sample introduction unit can control the laser optical system to narrow the scanning range for each set number of laser beam scans during laser ablation, and the analysis unit can extract and analyze only the data from the scanning range at a common position in the depth direction of the solid sample.

[0054] As yet another form of control, the sample introduction section can control the laser optical system so as to change the focal height of the laser relative to the solid sample for each set number of laser beam scans during laser ablation, thereby enabling analysis in the depth direction to be performed always with the same beam diameter.

[0055] The present invention can also use software to support analysis and correction, such as MassHunter from Agilent Technologies. EXAMPLES

[0056] In the following examples, the LA-ICP-MS was configured as shown in FIG. 1. A laser blender Raijin α, a laser ablation device manufactured by Seishin Shoji Co., Ltd., was used as the laser ablation (LA) section 10. A solid sample 101 of up to 50 mm×25 mm can be placed in a sample cell 102 on a stage 106 of the LA section 10. A window through which laser light can pass is provided at the top of the sample cell 102, and the solid sample surface can be irradiated with a quadruple wave (1 / 4 wavelength) femtosecond laser via a galvanometer mirror. The sample cell is provided with a connection port for an inlet pipe 108 through which He is supplied as a carrier gas, and an outlet pipe 109 connected to the sample inlet section 15.

[0057] The inductively coupled plasma mass spectrometer (ICP-MS) used was an Agilent 8900 triple quadrupole ICP-MS manufactured by Agilent Technologies, Inc. In the sample introduction section 15, a three-way joint was connected to a resin tube extending from the nebulizer, and the three-way joint was connected to the outlet tube 109 from the LA section 10.

[0058] First, the calibration curve data was prepared using XSTC-622 (1% nitric acid) manufactured by SPEX, USA, as the solution standard, with the necessary element standards added. Y, Rh and Ti were added as internal standard elements. Three different metal solid certified reference materials, CRM-191-2 (dynamo steel), BAM-310 (98.5% Al), and ERM-EB385 (pure copper), were used as the solid samples to be analyzed. The same internal standard elements were added as the auxiliary liquid introduced into the plasma together with the fine particle aerosol to be laser ablated, and 1% dilute nitric acid that was matrix-matched to the solution standard was used to mass analyze the laser ablated solid samples by wet plasma. The content data of elements in the solid samples was obtained from the obtained elemental analysis data and the calibration curve data, and the sum of all element nodes was corrected to 100%. The results are shown in Table 1.

[0059] [Table 1] [Industrial Applicability]

[0060] The analytical method and apparatus of the present invention are useful in applications where it is desired to perform highly accurate elemental analysis of various solid surfaces, such as solid surfaces of pure metals and alloys, without the use of solid standards. [Explanation of symbols]

[0061] 10 Laser Ablation (LA) Department 15 Sample introduction section 20 Ionization section 101 Solid Samples 102 Sample Cell 103 Laser Oscillator 104,105 Galvano mirror 106 Stages 153 Nebulizer 154 Spray Chamber

Claims

1. A plasma elemental analysis method for quantifying constituent elements of a solid sample without using a solid standard, comprising: The solution standard is atomized by a nebulizer, introduced into the plasma, excited and ionized, and subjected to spectroscopic analysis or mass analysis, thereby creating calibration curve data for elements contained in the solution standard; A solid sample placed in a sealed cell is atomized by laser ablation, and the atomized solid sample is introduced into a plasma together with an auxiliary liquid atomized by a nebulizer using a gas supplied to the cell, where it is excited and ionized for spectroscopic or mass spectrometry, thereby producing elemental analysis data for the elements contained in the solid sample. obtaining a concentration of a measurement element in the solid sample from the elemental analysis data and the calibration curve data; The total concentration of the measured elements is normalized to 100%, thereby correcting and quantifying the concentrations of the measured elements; The analytical method, wherein the solution standard and the auxiliary liquid contain one or more types of internal standard elements, and correction using the internal standard elements is performed when quantifying the measured element.

2. A plasma elemental analysis method for quantifying constituent elements of a solid sample without using a solid standard, comprising: The solution standard is atomized by a nebulizer, introduced into the plasma, excited and ionized, and subjected to spectroscopic analysis or mass analysis, thereby creating calibration curve data for elements contained in the solution standard; A solid sample placed in a sealed cell is atomized by laser ablation, and the atomized solid sample is introduced into a plasma together with an auxiliary liquid atomized by a nebulizer using a gas supplied to the cell, where it is excited and ionized for spectroscopic or mass spectrometry, thereby producing elemental analysis data for the elements contained in the solid sample. obtaining a concentration of a measurement element in the solid sample from the elemental analysis data and the calibration curve data; The total concentration of the measured elements is normalized to 100%, thereby correcting and quantifying the concentrations of the measured elements; An analytical method in which the measured element is a compound with another element, and standardization is performed by multiplying the concentration of the measured element by a coefficient calculated from the known composition of the compound.

3. 3. The analytical method according to claim 1, wherein calibration curve data for the measurement elements in the solid sample that are not contained in the solution standard are prepared based on semi-quantitative coefficients and calibration curve data for the measurement elements contained in the solution standard.

4. 3. The analytical method according to claim 1, wherein the microparticulated solution standard is introduced into plasma together with the laser-ablated solid sample microparticles to generate the calibration curve data.

5. 3. The analytical method according to claim 1 or 2, wherein the auxiliary liquid atomized by the nebulizer is mixed with the solid sample atomized by laser ablation in the spray chamber or at the rear of the spray chamber.

6. The analytical method according to claim 1 or 2, wherein the laser is a femtosecond laser.

7. The analytical method according to claim 1 or 2, wherein the plasma elemental analysis is ICP-OES or ICP-MS.

8. A plasma elemental analyzer for quantifying constituent elements of a solid sample without using a solid standard, comprising: a spectroscopic analysis section or mass analysis section for exciting and ionizing a sample introduced from a sample introduction section with plasma to perform elemental analysis; the sample introduction unit includes a sealed cell that atomizes a solid sample by laser ablation and introduces the atomized solid sample together with a carrier gas into the plasma, and a nebulizer that atomizes a solution standard and an auxiliary liquid separately and introduces the atomized solid sample into the plasma; The spectroscopic analysis unit or the mass analysis unit is Calibration curve data is created for elements contained in the solution standard that is atomized by a nebulizer and introduced into the plasma; After being atomized by laser ablation, the solid sample is introduced into the plasma by merging with the auxiliary liquid atomized by the nebulizer. The elements contained in the solid sample are excited and ionized to create elemental analysis data. obtaining a concentration of a measurement element in the solid sample from the elemental analysis data and the calibration curve data; The total concentration of the measured elements is normalized to 100%, thereby correcting and quantifying the concentration of the measured elements; The analytical apparatus wherein the solution standard and the auxiliary liquid contain one or more types of internal standard elements, and correction using the internal standard elements is performed when quantifying the measured element.

9. A plasma elemental analyzer for quantifying constituent elements of a solid sample without using a solid standard, comprising: a spectroscopic analysis section or mass analysis section for exciting and ionizing a sample introduced from a sample introduction section with plasma to perform elemental analysis; the sample introduction unit includes a sealed cell that atomizes a solid sample by laser ablation and introduces the atomized solid sample together with a carrier gas into the plasma, and a nebulizer that atomizes a solution standard and an auxiliary liquid separately and introduces the atomized solid sample into the plasma; The spectroscopic analysis unit or the mass analysis unit is Calibration curve data is created for elements contained in the solution standard that is atomized by a nebulizer and introduced into the plasma; After being atomized by laser ablation, the solid sample is introduced into the plasma by merging with the auxiliary liquid atomized by the nebulizer. The elements contained in the solid sample are excited and ionized to create elemental analysis data. obtaining a concentration of a measurement element in the solid sample from the elemental analysis data and the calibration curve data; The total concentration of the measured elements is normalized to 100%, thereby correcting and quantifying the concentration of the measured elements; An analytical apparatus in which the measured element is a compound with another element, and standardization is performed by multiplying the concentration of the measured element by a coefficient calculated from the known composition of the compound.

10. The spectroscopic analysis unit or the mass analysis unit is 10. The analytical apparatus according to claim 8, wherein calibration curve data for the measurement elements in the solid sample that are not contained in the solution standard are prepared based on semi-quantitative coefficients and calibration curve data for the measurement elements contained in the solution standard.

11. 10. The analytical apparatus of claim 8 or 9, wherein the nebulizer has a spray chamber, and the sample introduction section mixes the solid sample atomized by the laser ablation with the auxiliary liquid atomized by the nebulizer within the spray chamber or at a rear of the spray chamber.

12. 10. The analytical apparatus according to claim 8, wherein the spectroscopic analysis section or the mass analysis section creates the calibration curve data by introducing the particulate solution standard together with the laser-ablated solid sample particulates into plasma.

13. 10. The analytical device according to claim 8, wherein the sample introduction section narrows the scanning range for each set number of laser beam scans during the laser ablation, thereby eliminating an effect of edges of the scanning range on quantitative analysis in the depth direction of the sample.

14. 10. The analytical apparatus of claim 8 or 9, wherein the sample introduction section narrows the scanning range for each set number of laser beam scans during the laser ablation, and the spectroscopic analysis section or mass analysis section extracts and analyzes only data from a common scanning range in the depth direction of the sample.

15. 10. The analytical device according to claim 8, wherein the sample introduction section changes a focal height of the laser for each set number of laser beam scans during the laser ablation, and performs depth direction analysis with a constant beam diameter.

16. The analytical device according to claim 8 or 9, wherein the plasma elemental analysis is performed by ICP-OES or ICP-MS.

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