Plasma element analysis method and device

Abstract

To provide an analysis method and device using laser ablation and a plasma ion source without requiring a solid standard.SOLUTION: A plasma element analysis method and device are provided, the method comprising atomizing a solution standard using a nebulizer and introducing the same into a plasma, creating a calibration curve data for an element contained in the solution standard, atomizing a solid sample to be measured using laser ablation, introducing the solid sample into the plasma together with an auxiliary liquid from the nebulizer to ionize the same and generate element analysis data, acquiring the concentration of a measured element in the solid sample from the element analysis data and the calibration curve data, and correcting and quantifying the concentration of the measured element.SELECTED DRAWING: Figure 1

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, particularly 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] ICP-MS, a mass spectrometry method using a plasma ion source, is useful for analyzing inorganic elements, especially trace amounts of metals, and is widely used in many fields, including the semiconductor, geological, and environmental industries. ICP-MS enables multi-element analysis of most elements in the periodic table virtually simultaneously, and quantification of element concentrations can be performed at excellent sensitivity levels of parts per billion (ppb) or parts per trillion (ppt).

[0003] Similarly, ICP optical emission spectrometry, an analytical method that uses a plasma ion source, is suitable for the 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 the emission intensity can be used to rapidly measure a large number of elements.

[0004] Analytical methods using plasma ion sources are also useful for analyzing solid samples. 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 risk of the sample being contaminated by acid. Furthermore, since the entire solid sample must be decomposed with acid, it is not suitable for local analysis. In contrast, when using laser ablation (LA) 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 earth science.

[0005] For example, Patent Document 1 describes a technology that uses an LA-ICP-MS device to measure elements such as carbon, which have been difficult to measure in the past, 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 element in the measurement sample.

[0006] Patent Document 2 also 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 portion and the ICP signal intensity of a sample obtained by heating and vaporizing a standard liquid sample containing known amounts of elements contained in this solid sample using the ETV method. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-347473 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-136190 Summary of the Invention [Problem to be solved by the invention]

[0008] Using LA sample introduction, not only can solid samples be rapidly analyzed by ICP-MS or ICP-OES without pretreatment with acid, but also localized analysis and imaging analysis within 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 the resulting aerosol particles are introduced into the plasma, ionized, and subjected to elemental analysis.

[0009] Conventionally, when quantitatively analyzing solids using laser ablation, standard materials such as glass standard materials and steel standard materials have been used. For example, in Patent Document 1, it is 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, making them difficult to use if they do not match the target of analysis. Furthermore, if the target of analysis and the matrix differ, differences in the ionization efficiency of the elements occur, resulting in different signal intensities, which may make it difficult to accurately measure the element concentration in the sample.

[0010] Therefore, quantitative analysis is possible for materials for which standard samples can be prepared manually, such as various steel materials and glass materials with a SiO2 main component, but accurate quantitative analysis is difficult when standard samples of materials with similar chemical compositions are difficult to prepare manually, and the range 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 a solid standard sample. [Means for solving the problem]

[0012] According to one embodiment of the present invention, there is provided a plasma elemental analysis method for quantifying the 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, thereby creating calibration curve data for the elements contained in the solution standard. The solid sample to be measured is placed in a sealed cell, atomized by laser ablation, and introduced into the plasma together with an auxiliary liquid atomized, for example, by a nebulizer, by a gas supplied to the cell. The sample is excited and / or ionized, and subjected to mass spectrometry, thereby creating elemental analysis data 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 can be generated in either order. The elemental analysis data and the calibration curve data are used to obtain the concentration of the measured element in the solid sample, and the quantification is performed by correcting the concentration of the measured element.

[0014] A solid sample may contain a measurement element that is not included 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 for the measurement element contained in the solution standard. The semi-quantitative coefficient can be created for all elements by measuring a standard solution containing multiple elements with known concentrations, and represents the relative sensitivity of each element. Calibration curve data for a measurement element that is not included in the solution standard can be created based on the semi-quantitative coefficient obtained in advance and the calibration curve data for the 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 through 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, an analytical apparatus may perform the analytical method according to the present invention. That is, the analytical apparatus may generate calibration curve data in an analytical section for elements contained in a solution standard that has been atomized by a nebulizer and introduced into plasma. If a solid sample contains a measurement element that is not contained in the solution standard, the analytical apparatus may optionally generate calibration curve data for such measurement element based on the semi-quantitative coefficient of the measurement element and the calibration curve data for the measurement element contained in the solution standard.

[0017] The solid sample is atomized by laser ablation, then combined with the auxiliary liquid atomized by the nebulizer and introduced into the plasma, where it is excited and / or ionized to generate elemental analysis data. The creation of the calibration curve data and the elemental analysis data can be performed 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 normalizing the total concentration of the measured element obtained by the analytical device, for example, normalizing to 100%. That is, when the concentrations of the measured element obtained from the calibration curve data and the elemental analysis data are added, the result is usually different from 100% by mass. In this case, normalizing the total to 100% can more appropriately display the composition ratio of the constituent elements of the solid sample.

[0019] However, if the composition of the main components of a solid sample is known, the analytical unit may normalize to the amount of a component other than the main component, in which case normalization may be, 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. Furthermore, 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, e.g., dilute nitric acid at the same concentration, e.g., 1% or 3% by mass. As described above, the auxiliary liquid is aerosolized and introduced into the plasma together with the laser-ablated solid sample particles. In other words, the solid sample particles are introduced into the plasma in a wet state. It has been found that the use of an auxiliary liquid in the plasma (wet plasma) in this way increases the sensitivity of elemental analysis by several times.

[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 large particles of the solid sample to fall off. The mixing in the spray chamber may be performed at the rear of the spray chamber. [Effects of the Invention]

[0022] The present invention provides an analytical method and apparatus that can perform plasma elemental analysis of the type and concentration of elements in a solid sample with high accuracy without requiring a solid standard sample or a matrix-matched standard material, particularly an analytical method and apparatus that uses laser ablation and a plasma ion source, such as LA-ICP-MS or LA-ICP-OES. [Brief explanation of the drawings]

[0023] [Figure 1]FIG. 1 is a schematic diagram of a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) according to one exemplary embodiment of the present invention. [Figure 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 INVENTION

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

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

[0026] In this LA unit 10, laser light of a predetermined wavelength emitted from a laser oscillator 103 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 then irradiated onto the surface of the solid sample 101 to be analyzed. Examples of ablation lasers that can be used include a 213 nm or 266 nm Nd:YAG laser and a 193 nm excimer laser, but a femtosecond (fs) pulse width laser is preferred. Using a short-wavelength laser reduces the size of the sample aerosol, promotes ionization within the plasma, suppresses elemental fractionation, and also suppresses increased matrix effects and spike-like signals due to a decrease in plasma temperature.

[0027] Furthermore, the use of ultrashort pulse lasers such as femtosecond lasers makes it possible to analyze samples with high thermal conductivity without heating or melting them, and it is particularly possible to obtain particles that more accurately reflect the elemental composition of the bulk material, especially for materials with low melting points and high thermal conductivity, such as metals and alloys.

[0028] Connected to the sample cell 102 are an inlet pipe 108 that introduces a carrier gas made of a rare gas such as helium or argon, and an outlet pipe 109 that leads the gas out of the sample cell 102. 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 laser light.

[0029] In one specific embodiment, an ultrashort pulse (femtosecond) deep ultraviolet laser (FHG: quadruple harmonic generation) emitted from a laser oscillator 103 is reflected by galvanometer mirrors 104 and 105 in the X-axis and Y-axis directions and focused by an fθ lens 107 to ablate the solid sample 101. The solid sample 101 is instantaneously heated and vaporized by the ablation, but then re-aggregates (re-condenses) to form fine particles. The fine particles (aerosol) thus generated are several hundred nanometers in size and are transported from an outlet tube 109 to the sample introduction section 15 by a carrier gas such as helium or argon supplied from an inlet tube 108 to the sample cell 102. Argon can be mixed here to improve transport efficiency to the ionization section 20 (see the arrow in Figure 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 at 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 within the chamber, and a portion of it is led to the plasma in the ionization section 20. The remainder may be discharged via 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 contain auxiliary liquids, such as solution standards or aqueous nitric acid solutions, in accordance with embodiments of the present invention, as well as various tuning solutions, calibration solutions, rinse solutions, and the like. Automation configured to switch between various vials can also be included.

[0032] Microparticles or aerosols generated by laser ablation from solid sample 101, aerosols of solution standards or auxiliary liquids drawn up from vial 151 by pump 152 and atomized by nebulizer 153, and / or both are introduced into ionization section 20 through 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 pipe 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 mix 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 larger particle sizes 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 unit 20 through the sample introduction unit 15. Elements contained in the sample are decomposed and ionized by high-temperature plasma generated by high-frequency electromagnetic induction in the ionization unit 20. The ionization unit 20 typically includes a plasma torch for generating plasma, and an interface unit 25, which 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 unit 20 are sampled by the interface unit 25 and focused by the ion lens unit 30 to form an ion beam. The ions are then incident on the mass separation unit 35, which is typically composed of a quadrupole mass filter, to allow only ions of a selected mass-to-charge ratio (m / z) to pass through.

[0035] The mass separation unit 35 is configured so that only ions with a specific mass-to-charge ratio can 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 that make up the quadrupole mass filter, with the polarities of these electrodes being the same (the polarities of one pair of rod electrodes are opposite to those of the other pair of 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. These mass-to-charge ratio and mass resolution settings may be set by the system control unit 60 in response to desired input settings by an operator via, for example, an external computing device 70 of the mass analyzer.

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

[0037] The ion lens in the ion lens unit 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 electrostatic lenses that use an electric field to change the trajectory of ions, and is configured so that the ion transmittance changes accordingly when the voltage applied to the electrodes of the ion lens changes. Therefore, the ion lens voltage driver 55 can be controlled by the system control unit 60 to appropriately change the voltage applied to the ion lens electrodes, thereby increasing or decreasing the ion transmittance 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 the isotope of the 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 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, and data such as measured ion intensity (ion counts) can be transferred to the computing device 70 to perform arithmetic processing to determine the ion intensity of isotope ions of the analyte element being measured, as well as input / output processing with the user.

[0039] When the analysis is an optical emission spectroscopy such as ICP-OES, as is well known, 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 using, for example, a photomultiplier tube.

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

[0041] A standard solution containing a large number of elements can be used as a solution standard. Various such standard solutions are commercially available, and matrices such as nitric acid, hydrochloric acid, and sulfuric acid are used. For example, SPEX, Inc. in the United States, sells standard solutions containing various elements at certified concentrations. For example, a standard solution containing 35 elements, such as XSTC-622, can be used. When creating a calibration curve, the concentrations can be diluted as appropriate, and more than one type of solution standard can be used.

[0042] 1, the standard solution is diluted with, for example, ultrapure water with a resistivity of 18.0 MΩ or higher, placed in vials 151 at several different elemental concentrations, and then introduced into the plasma of the ionization unit 20 via nebulizer 153 and sample introduction unit 145 using pump 152 in contact with the solution. Mass analysis is performed using 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 calibration curves for as many elements as possible. Therefore, a solution standard can be created by appropriately combining standard solutions to cover all elements in the sample.

[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 the internal standard element is added to the auxiliary liquid introduced from the nebulizer when measuring a sample. Multiple internal standard elements can be added, rather than just one, which has the advantage of being able to correct for matrix effects that affect mass bias. 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 together with an auxiliary liquid, and introduced into the plasma, where it is ionized to generate elemental analysis data. For atomization by laser ablation, as shown in Figure 2, a solid sample 101 to be analyzed is placed in a sample cell 102 of appropriate size mounted on a stage 106. After performing positioning such as leveling 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 a pattern appropriate for the application, such as a line, raster, or single point pattern.

[0045] The atomized solid sample 101 is introduced into the ionization unit 20 of the ICP-MS via the sample introduction unit 15 from the sample cell 102 using a carrier gas such as helium. At this time, an auxiliary liquid may be simultaneously introduced from a vial 151 using a 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 particle aerosol into the ionization unit 20 together with the auxiliary liquid, the detection sensitivity of the ICP-MS can be increased compared to when no auxiliary liquid is 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 large particle diameters of the fine particles introduced from the LA unit 10 through the drain.

[0047] The signal intensities of the elements in 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 processing unit 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 processing unit 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 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 difference in signal intensity 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 determine the correct concentration.

[0049] Furthermore, according to one embodiment of the present invention, the concentrations of the measured elements thus obtained are corrected and normalized. LA-ICP-MS is capable of measuring all elements in the solid sample 101, and by using the calibration curve data created for many elements as described above, content data for almost all of the constituent elements constituting the solid sample 101 can be obtained. Because almost all constituent elements of the solid sample are measured in this way, the total of all measured element concentrations can be corrected to, for example, 100%, thereby making it possible to correct for variations in the ablation amount. In other words, although the amount of laser ablation from the solid sample 101 can vary depending on the material (e.g., steel sample vs. resin sample) and surface condition (e.g., flat sample vs. textured sample), in the present invention, by correcting the concentration relative to the total value of all measured element concentrations, any differences 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 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 major component compositions, such as samples containing 30% or 50% of a given major component, these major components may not be measured, and the total measured element concentrations may be normalized to 70% or 50%. Examples of such cases include compounds containing elements that cannot be measured by ICP-MS, such as fluorides (e.g., CaF), nitrides (e.g., GaN), or oxides (e.g., CaO); alloys with known ratios of Al, Co, Ni, etc. cannot be measured for all major components; and plastics where the mass percentage of C is known using other analytical methods, where the concentrations of some major components are known. In the case of CaF, GaN, CaO, etc., Ca and Ga may be measured, and compound correction based on the known composition (chemical formula) may be performed before 100% normalization.

[0052] When obtaining a depth profile of a solid sample, if the same area is scanned layer by layer with a laser, the edges formed in the solid sample by ablation can affect accurate analysis of each layer. According to one embodiment of the present invention, the scanning range can be narrowed as the depth increases. That is, the sample introduction unit controls the laser optical system to narrow the scanning range for each set number of laser beam scans during laser ablation, thereby eliminating the effect of the edges of the scanning range on the quantitative analysis of the solid sample depth.

[0053] As another form of control, the sample introduction unit can control the laser optical system so as 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 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 with the same beam diameter at all times.

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

[0056] In the following examples, the LA-ICP-MS was configured as shown in Figure 1. A Laser Blender Raijin α, a laser ablation device manufactured by Seishin Shoji Co., Ltd., was used as the laser ablation (LA) unit 10. A solid sample 101 measuring up to 50 mm x 25 mm can be placed in a sample cell 102 on a stage 106 of the LA unit 10. A window that allows laser light to pass through is provided at the top of the sample cell 102, enabling the solid sample surface to be irradiated with a fourth-harmonic (1 / 4 wavelength) femtosecond laser via a galvanometer mirror. The sample cell is equipped 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 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-pronged joint was connected to a resin tube extending from the nebulizer, and this was then connected to the outlet tube 109 from the LA section 10.

[0058] First, calibration curve data was prepared using XSTC-622 (1% nitric acid) solution standards (manufactured by SPEX, USA) supplemented with the necessary elemental standards. 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. Furthermore, the same internal standard elements were added to the auxiliary liquid introduced into the plasma along with the laser-ablated fine particle aerosol. 1% dilute nitric acid, matrix-matched to the solution standards, was used to analyze the laser-ablated solid samples by wet plasma mass spectrometry. The elemental content data in the solid samples was obtained from the obtained elemental analysis data and 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 the solid surfaces of pure metals and alloys, without using 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 Galvanometer mirror 106 Stages 153 Nebulizer 154 Spray Chamber

Claims

1. A plasma elemental analysis method for quantifying constituent elements of a solid sample, comprising: atomizing the solution standard, introducing the atomized solution standard into the plasma, exciting and / or ionizing the atomized solution standard, and subjecting the atomized solution standard to spectroscopic analysis or mass analysis; and creating calibration curve data for the 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 by a gas supplied to the cell, and excited and / or ionized to perform spectroscopic analysis or mass analysis, thereby generating elemental analysis data for the elements contained in the solid sample; obtaining the concentration of the measurement element in the solid sample from the elemental analysis data and the calibration curve data; and quantifying the measured element by correcting the concentration.

2. 2. 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.

3. The analytical method according to claim 1, wherein the solution standard and the auxiliary liquid are atomized by a nebulizer.

4. 2. The analytical method according to claim 1, 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.

5. 2. The analytical method according to claim 1, wherein the correction of the concentration of the measured element is performed by normalizing the total of the acquired concentrations of the measured element.

6. The analytical method of claim 5, wherein the normalization is 100% normalization.

7. 6. The analytical method according to claim 5, wherein the sum of the concentrations of the elements to be measured is a known value of N%, and the normalization is N% normalization.

8. 6. The analytical method according to claim 5, wherein the measured element is a compound with another element, and normalization is performed by multiplying the concentration of the measured element by a coefficient calculated from the known composition of the compound.

9. 2. 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.

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

11. The analytical method of claim 1 , wherein the laser is a femtosecond laser.

12. The analytical method according to any one of claims 1 to 11, wherein the plasma elemental analysis is ICP-OES or ICP-MS.

13. A plasma elemental analyzer for quantifying constituent elements of a solid sample, comprising: an analysis section for exciting and / or ionizing a sample introduced from the sample introduction section with plasma to perform elemental analysis; The analytical device, wherein the sample introduction section 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.

14. The analysis unit Calibration curve data is created for elements contained in the solution standard that has been atomized by a nebulizer and introduced into the plasma. A solid sample is atomized by laser ablation, and then the solid sample is introduced into the plasma after being merged with the auxiliary liquid atomized by a nebulizer, and the solid sample is excited and / or ionized to generate elemental analysis data; Optionally, preparing calibration curve data for a measurement element in the solid sample that is not included in the solution standard based on a semi-quantitative coefficient and the calibration curve data for the measurement element; obtaining the concentration of the measurement element in the solid sample from the elemental analysis data and the calibration curve data; The analytical device according to claim 13, wherein the concentration of the measured element is corrected and quantified.

15. 15. The analytical device according to claim 14, wherein the solution standard and the auxiliary liquid contain one or more types of internal standard elements, and the analytical unit performs correction using the internal standard elements when quantifying the measured elements.

16. The analytical device according to claim 14 , wherein the analysis unit corrects the concentration of the measured element by normalizing the acquired sum of the concentrations of the measured element.

17. 17. The analytical device of claim 16, wherein the normalization is 100% normalization.

18. 17. The analytical device of claim 16, wherein the sum of the concentrations of the measurement elements is a known value of N%, and the normalization is N% normalization.

19. The analytical device of claim 14, 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.

20. 15. The analytical device according to claim 14, wherein the analytical section generates the calibration curve data by introducing the atomized solution standard into plasma together with the laser-ablated solid sample particles.

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

22. 14. The analytical device of claim 13, wherein the sample introduction unit narrows the scanning range for each set number of laser beam scans during the laser ablation, and the analysis unit extracts and analyzes only data from a scanning range that is common in the depth direction of the sample.

23. 14. The analytical device according to claim 13, wherein the sample introduction section changes the focal height of the laser for each set number of laser beam scans during the laser ablation, and performs depth direction analysis with the same beam diameter at all times.

24. The analytical device according to any one of claims 13 to 23, wherein the plasma elemental analysis is ICP-OES or ICP-MS.

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