Method and apparatus for evaluating mass spectrometry results

Abstract

The present invention provides evaluation related to quantification of a measurement sample using an inductively coupled plasma mass spectrometry device. A pre-scan of the measurement sample is performed to obtain pre-scan data, and a quantification scan of the measurement sample is performed to obtain quantification scan data for at least one target element. Based on signal intensities obtained using the pre-scan data, the degree of mass spectral interference to signal intensities in the quantification scan data corresponding to mass numbers of the at least one target element is estimated, and a quantification result for the at least one target element in the quantification scan data is evaluated based on the estimated degree of mass spectral interference.

Description

Technical Field

[0001] This invention relates to ICP-MS (Inductively Coupled Plasma Mass Spectrometry), and more specifically, to a method and apparatus for evaluating the reliability of quantitative results obtained using ICP-MS. The method of this invention can be executed according to a computer program, and the computer program can be implemented in an ICP-MS apparatus. Background Technology

[0002] ICP-MS is used to analyze inorganic elements, especially metals present in trace amounts, and is widely used in many fields, including semiconductors, geology, and the environment. ICP-MS can perform essentially simultaneous multi-element analysis of most elements in the periodic table, and can also quantitatively determine element concentrations with excellent sensitivity at the parts-per-billion (ppb) or parts-per-trillion (ppt) level.

[0003] In ICP-MS, an inductively coupled argon plasma at atmospheric pressure is used as the ionization source. Analyte element ions generated in the plasma are introduced into a high-vacuum mass analyzer in the form of a beam using a differential pumping system. They are then separated and determined based on their m / z values. In one example, the analyte element is dissolved in a sample solution and delivered by a pump, along with an element added as an internal standard, to a nebulizer that generates a sample aerosol. The sample aerosol is supplied to the plasma, where it undergoes desolvation, atomization, and ionization. The resulting element ions are transported from the atmospheric pressure plasma to the mass analyzer through an interface comprising two perforated cones (called the sampling cone and the intercept cone) and through an ion lens assembly.

[0004] Due to the aforementioned configuration, when detecting weak signals from the target element, ICP-MS may be affected by mass spectrometric interference from argon in the plasma or from coexisting elements, potentially leading to signal intensity reduction. Mass spectrometric interference is a phenomenon where a component from another source overlaps in mass with the analyte being measured, and various types of mass spectrometric interference (such as isotope interference, polyatomic ion interference, and double-charged ion interference) can affect the accuracy of analytical results. Therefore, it is necessary to reduce or eliminate interference through appropriate methods to ensure the reliability of quantitative values.

[0005] To eliminate the effects of mass spectrometry interference, ICP-MS devices typically include a collision / reaction cell downstream of the ion lens assembly. The collision / reaction cell is designed to prevent interference with the measurement signal by introducing a reactive gas (such as hydrogen) or an inert gas (such as helium) with relatively low molecular weight, causing polyatomic / molecular ions in the incident ion beam to react with the reactive gas molecules and be selectively neutralized, or to collide with the inert gas molecules and lose kinetic energy. In some cases, a device is also used where mass analyzers are arranged in series upstream and downstream of the collision / reaction cell to more selectively eliminate mass spectrometry interference. Summary of the Invention

[0006] For practical use of ICP-MS, it is necessary to predict the interfering components of each target analyte in each individual sample, select the internal standard element to be used, and set the plasma conditions, gas conditions in the collision / reaction cell, integration time in the mass analyzer, etc. Users can refer to past measurement results to determine the required conditions. However, this relies heavily on experience and intuition, and is a tedious task requiring significant time and effort. If satisfactory results are not obtained, the measurement must be repeated to explore and optimize the conditions. Furthermore, there is usually no established method for evaluating quantitative results, and such evaluation also requires specialized knowledge. Therefore, verifying the reliability of the obtained quantitative results is extremely difficult.

[0007] For example, JP-A 2010-169412 discloses a method for semi-quantitative analysis of ICP luminescence analysis mass spectrometry data against a basic database to determine principal component elements, modifying the basic database by extracting information related to the principal component elements from an interference database, calculating the amount of interference to the determination of the sample at a predetermined measurement wavelength using the modified basic database, and displaying the amount of interference and the lower limit of quantitation at that measurement wavelength. However, JP-A 2010-169412 does not disclose any evaluation of the quantification values ​​or any display of reliability.

[0008] The problem this invention aims to solve is to rapidly identify mass spectrometry interferences superimposed on the signal of a target element quantified in a sample using ICP-MS, and the extent to which these interferences contribute to the signal intensity of each sample, and to provide an assessment of the reliability of the quantitative results without requiring additional time. Furthermore, another problem this invention aims to solve is to provide the assessment results obtained in this manner to the user in an easily understandable form, and to present information about the assessment content and details where necessary.

[0009] According to one embodiment of the present invention, a mass spectrometry analysis method is provided for quantifying at least one target element in a sample using an inductively coupled plasma mass spectrometer (ICP-MS). The method includes: performing a pre-scan of the sample to obtain pre-scan data; performing a quantitative scan of the sample to obtain quantitative scan data for the at least one target element; estimating the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to the at least one target element in the quantitative scan data based on the signal intensity obtained from the pre-scan; and evaluating the quantitative result of the at least one target element based on the estimated degree of mass spectrometry interference, according to the quantitative scan data. According to the present invention, the reliability of the quantitative scan data can be quickly assessed using the pre-scan data. This facilitates users in easily understanding the analytical accuracy and reliability of the quantitative results obtained from the quantitative scan.

[0010] According to one example of the invention, the pre-scan completes a scan of the entire m / z value range within a short time. That is, in the invention, by utilizing the information obtained from the pre-scan completed in a short time, mass spectrometry interferences in quantitative scans requiring a longer time can be identified, and the reliability of the data obtained from the quantitative scan can be quickly assessed. Here, the short time can be on the order of seconds, for example, within 10 seconds, preferably within 5 seconds, more preferably within 2 seconds, and even more preferably within 1 second.

[0011] Such pre-scans can be performed under the same mass spectrometry analysis conditions as quantitative scans, except for the integration time. The integration time is the time it takes for the mass analyzer to count the target ions, and can be set, for example, to approximately 0.1 to 10 seconds per scan. In this invention, the integration time can be set, for example, to 0.007 seconds per m / z value. However, other integration times may also be used.

[0012] For both pre-scanning and quantitative scanning, helium mode is preferred as the gas condition for the collision / reaction cell. However, in some cases, other cell gas conditions, including gas-free mode, may also be acceptable.

[0013] According to the method of the present invention, at least one target element can be quantified using data obtained from the quantitative scan, and the reliability of the quantification result can be evaluated based on the signal intensity obtained from the pre-scan. However, in some cases, the signal corresponding to an element based on the pre-scan data can be used as quantitative data for estimating the concentration of that element in the sample. In one example of the present invention, the concentration of an element in the sample can be estimated based on the pre-scan data using a response factor obtained according to plasma conditions and cell gas conditions. The response factor represents the relationship between an element and the signal intensity of that element and is defined according to mass spectrometry analysis conditions including at least plasma conditions, cell gas conditions, and sample introduction conditions. The response factor can also be defined considering other factors, such as sample uptake time, internal standard element, mass-to-charge ratio used in the mass analyzer, and integration time.

[0014] According to the present invention, based on the signal intensity obtained from the pre-scan, the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to the target element in the quantitative scan data is estimated. For example, based on the signal intensity of each m / z value in the pre-scan data, elements attributable to each m / z value are determined, the signal intensity of the mass spectrometry interference component corresponding to the m / z value of the target element is estimated, and the quantitative result of the target element based on the estimated mass spectrometry interference is evaluated based on the quantitative scan data. Mass spectrometry interference can be estimated based on pre-obtained interfering ion information, which involves the m / z values ​​and generation rates of compound ions and multivalent ions generated during the ionization of each element. In one example, interfering ion information is pre-obtained for various predefined condition settings (including plasma conditions and cell gas conditions of the collision / reaction cell, such as gas-free mode, helium mode, high-energy helium mode, and hydrogen mode), and the estimated signal values ​​of each element and interfering component are obtained based on this interfering ion information.

[0015] Plasma conditions may include: radio frequency power conditions; sampling depth, i.e., the positional relationship between the load coil and the sampling cone; central tube gas flow rate, including nebulizer gas, supplementary gas, and dilution / optional gas; central tube gas type, such as commonly used argon, oxygen added in the case of organic samples, and helium considered in the case of laser ablation; and / or wet / dry conditions, such as GC-ICP-MS or LA-ICP-MS conditions.

[0016] Pool gas conditions, i.e. conditions related to the collision / reaction pool, may include: the use or non-use of pool gas; the type of pool gas (e.g., He, H2, O2, 10% NH3 / He, CH4, or mixtures thereof); and / or interference reduction mechanisms (e.g., KED (kinetic energy discrimination), CID (collision-induced dissociation), and / or reaction), etc.

[0017] Examples of interfering components in interfering ion information include isotopes of other elements, polyatomic / molecular ions originating from other elements, and multivalent ions of other elements. For monovalent ions M+ that interfere with each m / z value, M is usually known. ++ MO + MH + MAr + MM + MOH + These include various types of interfering ions. Furthermore, the generation rate of these interfering ions can be obtained by pre-calculating the ratio of the signal from a sample of known concentration to the signal of the resulting interfering ions. The types and generation rates of interfering ions can be pre-listed for each element and stored as a reference table in the computer's memory. Multiple tables indicating the generation rate of interfering ions can be compiled based on plasma conditions, cell gas conditions, etc. The signal intensity of each interfering ion can be estimated by multiplying the signal intensity obtained from the pre-scan by the generation rate of that interfering ion.

[0018] Since the types and abundances of isotopes for each m / z value are known, the signal intensity of each isotope can be estimated by multiplying the signal intensity of the element containing that isotope by its corresponding isotopic abundance. In this way, the signal intensity corresponding to each element and the signal intensity corresponding to the interfering components of each element can be estimated, and based on this, the predicted mass spectrometry interference for each element can be estimated.

[0019] Therefore, by using the signal intensity corresponding to each element estimated using a pre-scan and the signal intensity corresponding to the mass spectrometry interference component, the quantitative results of at least one target element obtained by the corresponding quantitative scan can be evaluated. For example, this evaluation can be displayed on a monitoring display or the like along with an image of the periodic table, and the degree of mass spectrometry interference can be graded using percentage display, star rating display, and / or heatmap.

[0020] Furthermore, according to one embodiment of the invention, the invention can be implemented as a program for causing a computer to perform the above-described processing. This program, for example, can be provided as a computer program for quantitative mass spectrometry analysis of at least one target element in a sample using an inductively coupled plasma mass spectrometry (ICP-MS) device. The program causes the computer to perform the following steps: performing a pre-scan of the sample to obtain pre-scan data; performing a quantitative scan of the sample to obtain quantitative scan data for the at least one target element; estimating the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to the at least one target element in the quantitative scan data based on the signal intensity obtained from the pre-scan; and evaluating the quantitative result of the at least one target element based on the estimated degree of mass spectrometry interference, according to the quantitative scan data.

[0021] The step of estimating the degree of mass spectrometry interference can be performed, for example, based on the aforementioned interfering ion information stored in tables or the like. These steps may further include estimating the concentration of the element in the sample from the signal intensity using a response factor also stored in a storage device, based on the pre-scan data. The computer program may be provided as a downloadable program from a storage medium or via a network, or may be executed via a network without downloading.

[0022] Furthermore, according to one embodiment of the present invention, an inductively coupled plasma mass spectrometry (ICP-MS) apparatus that implements the above-described procedure is provided. Such an apparatus may, for example, include: one or more storage units configured to store pre-scan data obtained by performing a pre-scan on a measurement sample containing at least one target element for m / z values ​​within a predetermined range, and to store quantitative scan data about the at least one target element obtained by performing a quantitative scan on the measurement sample; and a controller configured to perform the following steps: estimating, based on the signal intensity obtained from the pre-scan, the degree of mass spectrometric interference affecting the signal intensity of the m / z value corresponding to the at least one target element in the quantitative scan data; and evaluating the quantitative result of the at least one target element based on the estimated degree of mass spectrometric interference according to the quantitative scan data.

[0023] According to one example, the one or more storage units may be, for example, a memory or a hard disk, and the controller may be, for example, a processor. The one or more storage units and the controller cooperate as needed according to the above procedure to perform corresponding operations. The one or more storage units may be further configured to store pre-obtained information on interfering ions, including m / z values ​​and generation rates of compound ions and multivalent ions generated during the ionization of each element. The one or more storage units are further configured to store a response factor obtained based on the elemental signal intensity according to plasma conditions and cell gas conditions, and the controller is further configured to perform the following step: using this response factor, estimating the concentration of the element in the measured sample from the signal intensity based on the pre-scan data.

[0024] According to one example, the device may further include a monitoring display configured to display an evaluation of the quantitative results. For example, the monitoring display may be configured to display an image as shown in the accompanying figures below. The displayed content may include an image of the periodic table and displays indicating the degree of mass spectrometry interference, such as percentage displays, star ratings, and / or heatmaps, thereby improving visual legibility.

[0025] According to the present invention, any user can easily understand the analytical accuracy and reliability of the obtained quantitative results without spending a lot of time or having ICP-MS expertise. If the reliability is insufficient, for example, the plasma conditions, the cell gas conditions of the collision / reaction cell, etc., can be modified to improve the reliability of the determination. This enables the improvement of the analytical accuracy and reliability of the quantitative results obtained by ICP-MS, and also helps to elucidate the causes and mechanisms of mass spectrometry interference. Attached Figure Description

[0026] [ Figure 1 ] Figure 1 This is a schematic diagram illustrating an example of an apparatus capable of performing mass spectrometry analysis according to the present invention. [ Figure 2 ] Figure 2 This is a flowchart illustrating an exemplary algorithm according to one embodiment of the present invention. [ Figure 3 ] Figure 3 This is a flowchart depicting an algorithm for estimating mass spectrometry interference according to one embodiment of the present invention. [ Figure 4 ] Figure 4 This is an example of an evaluation of quantitative results shown in association with an image of the periodic table. [ Figure 5 ] Figure 5 This is another example of an evaluation of quantitative results shown in association with an image of the periodic table. [ Figure 6 ] Figure 6 This is another example of an evaluation of quantitative results shown in association with an image of the periodic table. [ Figure 7 ] Figure 7 This is another example of an evaluation of quantitative results shown in association with an image of the periodic table. [ Figure 8 ] Figure 8 This is an example of a star rating display. [ Figure 9 ] Figure 9 This is another example of a star rating display. [ Figure 10 ] Figure 10 This is an example of using a heatmap on a periodic table image to display quantitative results for evaluation. [ Figure 11 ] Figure 11 This is a table illustrating an exemplary relationship between interference levels and reliability ratings. Detailed Implementation

[0027] Figure 1This is a schematic diagram illustrating an example of an apparatus capable of performing mass spectrometry analysis according to the present invention. An ICP mass spectrometry analysis apparatus 100 includes: an inductively coupled plasma ion source 130; an interface 140 for extracting elemental ions generated from a sample from the plasma; an ion lens assembly 150 for accelerating the extracted ions and delivering them as an ion beam; a collision / reaction cell 160 disposed downstream of the ion lens assembly; a mass filter 170 for separating elemental ions according to their mass; and a detector 180.

[0028] In the sample collection unit 110, a peristaltic pump 111 draws the sample 112 from the vial and delivers it to the nebulizer 121, which extends from one end of the temperature-controlled nebulization chamber 122 provided in the sample introduction unit 120. The sample collection unit 110 may include multiple vials, each containing the sample to be measured, various standard solutions, tuning solutions, calibration solutions, rinsing solutions, etc., and can automatically switch between them. The nebulizer 121 uses high-pressure argon (Ar) gas to atomize the sample to form a sample aerosol. This aerosol is blown into the ion source 130 after large droplets are removed by the nebulization chamber 122.

[0029] Ion source 130 has an ICP torch 131. This torch includes a series of concentric quartz tubes through which argon gas flows, these tubes being disposed within a radio frequency (RF) coil 132. The RF magnetic field generated by the coil excites Ar atoms passing through the torch, thereby enabling the generation and maintenance of a high-energy plasma. Sample aerosol is blown into the plasma, where it undergoes desolvation, atomization, and ionization.

[0030] In interface 140, ions are extracted from the plasma via sampling cone 141 and intercept cone 142. The extracted ions are then accelerated by ion lens assembly 150 and delivered as an ion beam into a collision / reaction cell 160 located downstream of ion lens assembly 150. Ion lens assembly 150 may include extraction electrode 151, a series of focusing lenses 152, and an off-axis mounted omega lens 153. Gas may be introduced into collision / reaction cell 160, as indicated by reference numeral 161. Such cells are known to remove polyatomic molecular ions from the incident ion beam that could interfere with the mass spectrometry, such as those comprising elements derived from carrier gas, plasma gas, and auxiliary gas, through charge transfer reactions and kinetic energy reduction induced by collisions with gas molecules. Cell 160 may also include a multi-electrode arrangement, such as a quadrupole mass filter 162.

[0031] A mass analyzer, including a mass filter 170 and a detector 180, is positioned downstream of the collision / reaction cell. The mass filter 170 may include, for example, a quadrupole mass filter 171, comprising four parallel rods to which RF and DC voltages are applied. For any given combination of RF and DC voltages applied to the rods, the mass filter delivers only ions with specific m / z values ​​to the detector 180. This allows ions of different elements to be separated by the mass filter and then measured by the detector 180. The detector 180 includes an electron multiplier tube detector 181 positioned immediately downstream of the mass filter. The ion signal at each mass-to-charge ratio is amplified and then measured using a multichannel counting device. The elemental signal intensity measured within a specified integration time is proportional to the concentration of that element in the sample solution.

[0032] The sample acquisition unit 110, sample introduction unit 120, inductively coupled plasma ion source 130, collision / reaction cell 160, mass filter 170, and other components can all be controlled by the system controller of the ICP mass spectrometry analyzer, which in turn can be controlled by a computer (such as a personal computer). The method of the present invention can be implemented as a computer-executed program. The computer configured to execute such a program, the ICP mass spectrometry analyzer 100 including such a computer, and the computer program itself all fall within the scope of the present invention.

[0033] In other words, according to one example, the method of the present invention can be implemented by... Figure 1 The computer program executed by the personal computer shown. The method may include: performing pre-scan and quantitative scans, predicting mass spectrometry interferences, and evaluating quantitative results using the device configuration of the shown inductively coupled plasma mass spectrometry apparatus. For example, the collision / reaction cell may operate in helium mode, and for the pre-scan, the integration time of detector 180 may be set to an extremely short time. Response factors indicating the relationship between element-to-element signal intensities and information on interfering ions may be compiled based on plasma conditions, cell gas conditions, etc., and may be stored in the built-in memory of the personal computer or in a database connected to the personal computer via a wired or wireless connection.

[0034] Through the input interface, the user instructs the computer or processor to set the conditions for pre-scan and quantitative scans, introduces the sample to be measured through the sample acquisition unit 110, performs the measurement, and obtains the pre-scan dataset and the quantitative scan dataset. The computer is capable of performing the following processing operations according to the program: evaluating the interference level of at least one target element, and determining the element concentration using the pre-scan data or quantitative scan data. The processing results, i.e., the mass spectrometry interference levels and details (such as interfering ion types) of each element predicted based on the pre-scan data, can be displayed on the monitor of a personal computer or... Figure 1 The monitor screen of the ICP-MS device shown. Example

[0035] Figure 2 A basic flowchart of an algorithm according to one embodiment of the present invention is shown. As described above, when a user sets conditions for an inductively coupled plasma mass spectrometry (ICP-MS) device, a pre-scan is first performed, followed by a quantitative scan, and the corresponding dataset is stored. However, the present invention is not limited to the order in which these scans are performed; in some cases, the scans can be performed in reverse order.

[0036] Pre-scan data obtained using ICP-MS can be used to calculate mass spectrometry interferences and, in some cases, to calculate concentrations using the response factor, as described below. Pre-scan data are obtained over a range of m / z values ​​suitable for analysis (e.g., from m / z 1 to m / z 260) with relatively short integration times (e.g., 0.007 seconds per m / z value), typically acquired immediately before quantification of the sample. As mentioned above, the mass analyzer conditions set for pre-scan measurements are the same as for quantitative scans, except for the integration time. Furthermore, the response factor can be corrected according to the device status of the inductively coupled plasma mass spectrometry apparatus.

[0037] All measurement data, such as m / z values, signal strength, and integration time, as well as other measurement-related metadata, can be accessed through the pre-scan dataset.

[0038] exist Figure 2 In the example of the algorithm shown, a quantitative scan is performed after a pre-scan, using ICP-MS to determine the sample containing at least one target element to obtain a quantitative scan dataset. This dataset is used for routine quantitative analysis by ICP-MS without measuring the m / z values ​​that are not required for the quantification of the at least one target element in the sample.

[0039] Next, the number of atomic numbers that can be assigned to each m / z value in the pre-scanned dataset is calculated. Let I(M) iso ) represents the isotope M corresponding to the element. iso Signal strength at [m / z]. I(M iso Based on the basic m / z value M base The signal strength at a given location is calculated, and this fundamental m / z value is the m / z value of a representative isotope of the element. Let A(M) iso ) represents isotope M iso The natural isotopic abundance of [m / z], and I(M base ) represents the basic m / z value M defined for this element. base The signal strength at that location. At this time, I(M) iso The calculation is as follows: The signal strength I(M) used in the calculation base) needs to exceed the minimum count I min .

[0040] When an m / z value has multiple candidate elements due to isotopes—for example, the signal intensity at m / z 50 includes contributions from isotopes of Ti, V, and Cr—it is typically necessary to identify that m / z value as corresponding to a specific element. Otherwise, element-specific parameters for a particular element, such as the response factor and the generation rate of mass spectrometry interference components, will not be applicable.

[0041] Let I(M) represent the signal intensity measured at m / z value M during the pre-scan. Count the number of isotopes that satisfy the following condition: When the number of isotopes is 1, isotope M iso [m / z] is considered to represent the majority of the signal at the m / z value M, and this isotope M iso The "element" from which [m / z] originates is the element predicted for the m / z value M. In other cases, the m / z value M cannot be identified as corresponding to a specific element.

[0042] When the m / z value M cannot be identified as corresponding to a specific element, the signal intensity of each mass spectrometry interference component is calculated for all m / z values. Figure 3 A flowchart illustrating the calculation of the signal intensity generated by mass spectrometry interference components for each m / z value is shown. The signal intensity generated by the mass spectrometry interference components can be calculated using the signal intensities contained in a pre-scan dataset obtained for all m / z values. For each m / z value, the mass spectrometry interference components originating from the element can be identified based on the interference generation rate. The interference generation rate is defined for each element based on pre-defined actual measurements for each condition setting, including cell gas and plasma conditions. The signal intensity I of the mass spectrometry interference components originating from the source element is shown. n (M) can be calculated as follows: Among them, M source Let m be the m / z value of the corresponding source element, and R(n) be the interference generation rate of this component.

[0043] Examples of interfering components include polyatomic / molecular ions originating from other elements, and multivalent ions from other elements. Monovalent ions M, which interfere with each m / z value, are another example. + The ions, M is known ++ MO + MH + MAr + MM + MOH +Furthermore, since the types and isotopic abundances of isotopes at each m / z value are known, the signal strength of each isotope as an interfering component, expressed in counts per second (CPS), can be estimated by multiplying the signal strength of the element with that isotope by the corresponding isotopic abundance.

[0044] When the m / z value M cannot be identified as corresponding to a specific element and an isotope exists at that m / z value, calculate the signal contribution from each isotope. The required signal strength I′(M) i The following can be calculated: Where I(M) i, j () is the signal intensity of each isotope calculated based on isotopic abundance. E represents the set of elements containing such isotopes. For example, a mass-to-charge ratio of 50 m / z represents a set of titanium, vanadium, and chromium.

[0045] Finally, based on the reliability of the quantitative results for the target element using the quantitative scanning data, the potential interference level determined by the pre-scanning dataset was used for evaluation. The interference level [%] was calculated based on the total signal intensity of the mass spectrometry interference components calculated from the pre-scanning dataset and the signal intensity I of the target element included in the quantitative scanning dataset. FQ Comparison between (M).

[0046] That is, the total mass spectrometry interference component S that may be superimposed on the signal at the m / z value M. intfs (M) [cps] is calculated as follows: Where I n (M) is the signal intensity of a single mass spectrometry interference component, and d n (M) is used to obtain I n (M) is the integration time of the signal at the source m / z value from which it originates.

[0047] On the other hand, the signal S at the m / z value M in the quantitative scanning data FQ (M) [cps] is calculated as follows: Where d FQ (M) is used to obtain signal strength I. FQ The integration time of (M).

[0048] Therefore, the interference level IL(M) [%] of the m / z value M is calculated as follows:

[0049] The interference level obtained in this way can assess the potential interference that may be superimposed on the signal at each m / z value in the quantitative scan data. In this way, the quantitative results of all target elements based on the quantitative scan data can be evaluated according to the interference level, and the reliability of the obtained quantitative results can also be evaluated according to the interference level. Figure 11 An example is shown showing the relationship between interference level and reliability, where the interference level is divided into five levels.

[0050] As described above, for m / z values ​​in the pre-scan dataset that can be identified as corresponding to a specific element, the corresponding concentration can be calculated by scaling the signal intensity corresponding to that element using a response factor. This allows us to determine the concentration of elements in the sample that act as sources of mass spectrometry interference.

[0051] Let i[m / z] represent a single isotope of element E. The response factor F corresponding to isotope i[m / z] is... SQ (i) The calculation is as follows: Among them, F SQ (E) is a response factor that can be obtained in advance based on the relationship between the element and the signal sensitivity. This relationship depends on the plasma conditions and the pool gas conditions. Abd(i) is the relative isotopic abundance of isotope i [m / z].

[0052] For example, while low-temperature plasma has advantages such as suppressing carrier gas ionization, reducing background noise, and improving sensitivity for light elements, it also has disadvantages. Specifically, for samples with high matrix, the matrix effect becomes more pronounced, and elements with high ionization potentials are less easily ionized. The response factor defines the relationship between an element and signal sensitivity under these conditions. A response factor corrected for device conditions can also be used. Therefore, the concentration C(M) corresponding to the m / z value M is calculated as follows:

[0053] According to the present invention, quantitative results assessment based on interference levels can be presented, for example, in a visually easily identifiable form, such as... Figures 4 to 10 As shown. This presentation method makes it easy to understand the reliability of the quantitative results for each measured sample. Figures 4 to 7 In this invention, the quantitative reliability of elements is displayed using a graph of the periodic table. Diagonally lined cells (e.g., Cr, Mn, Fe, and other elements) indicate no problem, while dark gray cells (e.g., ...) indicate no problem. Figure 6 The As and Se values ​​indicate the warning level. Quantitative reliability for specific elements is displayed using a star rating system, with five stars indicating high reliability and one star indicating low reliability. Additionally, potential overlapping or interfering components are shown.

[0054] Figure 4 The quantitative results assessment of NIST 1643f (a certified reference material for environmental water samples) is shown. Figure 5 , Figure 6 and Figure 7 The quantitative results of NIST 1643f with added rare earth elements (REEs) of 0.1 ppm, 1 ppm, and 10 ppm are shown. Interference signals from Nd and Sm doubly charged ions are expected to superimpose on the signal corresponding to As. Figures 4 to 7 The results shown indicate that the reliability of As quantification decreases with increasing REE concentration. These results can be readily understood by combining the star chart with an image of the periodic table.

[0055] Figure 8 The star rating system is used to display the quantitative results assessment details for the sample with 40 ppb Ba added. 136 Ba 2+ The generated signal may be superimposed on the signal corresponding to Zn at m / z 68, while the signal generated by... 138 Ba 2+ The generated signal may be superimposed on the signal corresponding to Ga at m / z69. Figure 8 The star ratings in the charts indicate the reduced reliability caused by such potential interference, as well as the presence of interfering substances.

[0056] Figure 9 Similarly, the evaluation of quantitative results for samples with 2% H2SO4 added is presented. Signals generated by sulfur oxides may superimpose on the signal corresponding to Ti at m / z 48, signals generated by sulfur hydroxides may superimpose on the signal corresponding to Ti at m / z 49, and signals generated by sulfur dimers may superimpose on the signal corresponding to Zn at m / z 66. This superposition leads to an increased level of interference, which is presented to the user along with the associated interfering substances via a star-rating display.

[0057] Figure 10 An example is shown, where... Figure 9 The concentrations associated with the results are displayed as a heatmap using an image of the periodic table. Cells representing sulfur indicate a higher concentration of sulfur in the sample. Users can immediately determine that the sample contains a relatively high concentration of sulfur.

[0058] As described above, by performing pre-scanning and quantitative scanning with different integration times, the pre-scanning data measurement time for each sample is only about two seconds. Figures 4 to 7 In the example shown, the quantitative scan of the sample takes approximately 4.5 minutes. Therefore, the additional time required to determine the pre-scan data is negligible, while providing crucial information about the reliability of the quantitative scan data quickly. Industrial applicability

[0059] The quantitative result evaluation method, procedure and apparatus provided by this invention can be widely used in the field of mass spectrometry analysis. List of reference numerals

[0060] 100 Inductively Coupled Plasma Mass Spectrometry Analyzer 110 Sample Collection Department 120 Sample Introducing Section 130 Inductively Coupled Plasma Ion Source 140 interface 150 Ion Lens Assembly 160 Collision / Reaction Pool 170 quality filter 180 detector

Claims

1. A mass spectrometry analysis method for quantifying at least one target element in a sample using an inductively coupled plasma mass spectrometer, the method comprising: Perform a pre-scan of the sample to obtain pre-scan data; Quantitative scanning of the sample is performed to obtain quantitative scanning data of the at least one target element; Based on the signal intensity obtained from the pre-scan, estimate the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to at least one target element in the quantitative scan data; as well as Based on the estimated level of mass spectrometry interference, the quantitative results of the at least one target element are evaluated according to the quantitative scanning data.

2. The method according to claim 1, wherein, The pre-scan completes the scan of the entire m / z value range in a short time.

3. The method according to claim 1, wherein, Except for the integration time, the mass spectrometry analysis conditions for the pre-scan are the same as those for the quantitative scan.

4. The method according to claim 1, wherein, Both the pre-scan and the quantitative scan were performed in helium mode.

5. The method according to claim 1, wherein, The signal intensity based on the pre-scan data was used to estimate the concentration of elements in the sample being measured.

6. The method according to claim 5, wherein, The concentration of the element is estimated using a response factor, which is obtained based on the plasma conditions and pool gas conditions, and on the signal strength of the element.

7. The method according to claim 1, wherein, The evaluation of the quantitative results is displayed together with the periodic table image.

8. The method according to claim 1, wherein, The degree of mass spectrometry interference is displayed in a graded manner using percentage display, star rating display, and / or heat map.

9. The method according to claim 1, wherein, The estimation of the mass spectrometry interference level based on the signal intensity obtained from the pre-scan is performed based on pre-obtained interfering ion information, which includes the m / z values ​​and generation rates of compound ions and multivalent ions generated during the ionization process of each element.

10. The method according to claim 9, wherein, The interfering ion information was obtained for various condition settings, including plasma conditions and measurement conditions used in the collision / reaction cell.

11. A computer program for mass spectrometry analysis, used to quantify at least one target element in a sample using an inductively coupled plasma mass spectrometer, said program causing the computer to perform the following steps: Perform a pre-scan of the sample to obtain pre-scan data; Quantitative scanning of the sample is performed to obtain quantitative scanning data of the at least one target element; Based on the signal intensity obtained from the pre-scan, estimate the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to at least one target element in the quantitative scan data; and Based on the estimated level of mass spectrometry interference, the quantitative results of the at least one target element are evaluated according to the quantitative scanning data.

12. The procedure according to claim 11, wherein, The step of estimating the degree of mass spectrometry interference is performed based on pre-obtained interfering ion information, which includes the m / z values ​​and generation rates of compound ions and multivalent ions generated during the ionization of each element.

13. The procedure according to claim 11, wherein, The step further includes: using a response factor to estimate the concentration of an element in the sample from the signal intensity based on the pre-scan data, the response factor being obtained based on the plasma conditions and cell gas conditions and the signal intensity of the element.

14. The procedure according to claim 11, wherein, The steps for evaluating the quantitative results include classifying and displaying the degree of mass spectrometry interference using percentage displays, star ratings, and / or heatmaps.

15. An inductively coupled plasma mass spectrometry device, comprising: One or more storage units are configured to store pre-scan data obtained by performing a pre-scan on a measurement sample containing at least one target element for m / z values ​​within a predetermined range, and to store quantitative scan data about the at least one target element obtained by performing a quantitative scan on the measurement sample. as well as The controller is configured to perform the following steps: Based on the signal intensity obtained from the pre-scan, estimate the degree of mass spectrometry interference affecting the signal intensity of the m / z value corresponding to at least one target element in the quantitative scan data; as well as Based on the estimated level of mass spectrometry interference, the quantitative results of the at least one target element are evaluated according to the quantitative scanning data.

16. The inductively coupled plasma mass spectrometry apparatus according to claim 15, wherein, The one or more storage units are further configured to store pre-obtained interfering ion information, which includes the m / z values ​​and generation rates of compound ions and multivalent ions generated during the ionization of each element, and the controller is configured to estimate the degree of mass spectrometry interference based on the interfering ion information.

17. The inductively coupled plasma mass spectrometry device according to claim 15, wherein, The one or more storage units are further configured to store response factors obtained based on element signal intensity according to plasma conditions and cell gas conditions, and the controller is further configured to perform the following steps: using the corresponding response factors, estimating the concentration of the element in the measured sample from the signal intensity based on the pre-scan data.

18. The inductively coupled plasma mass spectrometry apparatus of claim 15, further comprising a monitoring display configured to display an assessment of the quantitative results together with an image of the periodic table.

19. The inductively coupled plasma mass spectrometry device according to claim 18, wherein, The steps for evaluating the quantitative results include classifying and displaying the degree of mass spectrometry interference using percentage displays, star ratings, and / or heatmaps.

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