Quality analysis methods and ICP quality analysis apparatus

Abstract

According to the present invention, a liquid sample is introduced into an inductively coupled plasma (ICP) mass spectrometry device by way of a liquid chromatograph, in a sample introduction step. In an internal standard element introduction step, an internal standard element is introduced by mixing a solution of the internal standard element, not by way of the liquid chromatograph, into the liquid sample introduced in the sample introduction step. In a first chromatogram acquisition step, a first chromatogram 81 is acquired by performing mass spectrometry of each component of the liquid sample introduced by means of the sample introduction step. In a second chromatogram acquisition step, a second chromatogram 82 is acquired by performing mass spectrometry of the internal standard element introduced by means of the internal standard element introduction step. In a first correction step, the first chromatogram 81 is corrected using the second chromatogram 82.

Description

[Technical Field]

[0001] The present invention relates to a mass spectrometry method and an ICP mass spectrometer. [Background technology]

[0002] Inductively Coupled Plasma (ICP) mass spectrometers ionize elements in a liquid sample using plasma generated by inductive coupling, and then perform mass analysis on the ionized elements, enabling highly sensitive qualitative and quantitative analysis of the elements. However, ICP mass spectrometers cannot separate and analyze the chemical forms of each component in a liquid sample.

[0003] For example, when analyzing arsenic compounds as target components, it is generally known that inorganic arsenic compounds are more toxic than organic arsenic compounds, and trivalent arsenic compounds are more toxic than pentavalent arsenic compounds. As such, the toxicity of arsenic compounds differs depending on their chemical form, so it is preferable to separate the chemical forms of the target components before analyzing them.

[0004] Therefore, a mass spectrometry method using a configuration in which a liquid sample is introduced into an ICP mass spectrometer via a liquid chromatograph (LC-ICPMS) is known (see, for example, Patent Document 1 below). With this configuration, it is possible to separate the chemical forms of target components in a liquid sample using a liquid chromatograph, and then perform mass analysis for each chemical form. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 198811 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the target components in the liquid sample introduced into the ICP mass spectrometer may be affected by variations in ionization efficiency within the plasma or variations in behavior within the mass spectrometer, etc. In such cases, errors may occur in the measurement results, and therefore a configuration that can correct these errors is desirable.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a mass analysis method and an ICP mass spectrometer that are capable of correcting measurement errors that occur within the ICP mass spectrometer. [Means for solving the problem]

[0008] A first aspect of the present invention is a mass spectrometry method including a sample introduction step, an internal standard element introduction step, a first chromatogram acquisition step, a second chromatogram acquisition step, and a first correction step. In the sample introduction step, a liquid sample is introduced into an ICP mass spectrometer via a liquid chromatograph. In the internal standard element introduction step, the internal standard element is introduced by mixing a solution of the internal standard element with the liquid sample introduced in the sample introduction step without passing through the liquid chromatograph. In the first chromatogram acquisition step, a first chromatogram is acquired by mass spectrometry of each component in the liquid sample introduced in the sample introduction step. In the second chromatogram acquisition step, a second chromatogram is acquired by mass spectrometry of the internal standard element introduced in the internal standard element introduction step. In the first correction step, the first chromatogram is corrected using the second chromatogram.

[0009] A second aspect of the present invention is an ICP mass spectrometer into which a liquid sample is introduced via a liquid chromatograph, comprising an internal standard element introduction unit, a first chromatogram acquisition processor, a second chromatogram acquisition processor, and a first correction processor. The internal standard element introduction unit introduces the internal standard element by mixing a solution of the internal standard element with the liquid sample introduced from the liquid chromatograph without passing through the liquid chromatograph. The first chromatogram acquisition processor acquires a first chromatogram by mass spectrometry of each component in the liquid sample introduced from the liquid chromatograph. The second chromatogram acquisition processor acquires a second chromatogram by mass spectrometry of the internal standard element introduced from the internal standard element introduction unit. The first correction processor corrects the first chromatogram using the second chromatogram. [Effects of the Invention]

[0010] According to the present invention, it is possible to correct measurement errors that occur within an ICP mass spectrometer. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram illustrating an embodiment of an LC-ICP mass spectrometer. [Figure 2] FIG. 1 is a block diagram showing an example of the electrical configuration of an LC-ICP mass spectrometer. [Figure 3] FIG. 10 is a diagram for explaining a specific example of correction processing. [Figure 4] FIG. 10 is a diagram for explaining a specific example of correction processing. [Figure 5] 1 is a flowchart illustrating each step of mass spectrometry. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1. Overall configuration of LC-ICP mass spectrometer 1 is a block diagram showing one embodiment of an LC-ICP mass spectrometer. This LC-ICP mass spectrometer is a device that combines a liquid chromatograph 1 and an ICP mass spectrometer 2, and a liquid sample is introduced into the ICP mass spectrometer 2 via the liquid chromatograph 1.

[0013] The liquid chromatograph 1 includes a mobile phase reservoir 11, a first pump 12, a sample injector 13, a column 14, and a column oven 15. A mobile phase made of a liquid such as an organic solvent is stored in the mobile phase reservoir 11. The mobile phase in the mobile phase reservoir 11 is pumped out by driving the first pump 12 and supplied to the column 14. The first pump 12 is a liquid delivery pump constituted by, for example, a high-pressure pump, and pumps the mobile phase from the mobile phase reservoir 11 at a constant flow rate.

[0014] A liquid sample is injected at any timing from the sample injector 13 into the mobile phase supplied to the column 14. As a result, the liquid sample is supplied to the column 14 together with the mobile phase. The column 14 is housed in a column oven 15. The interior of the column oven 15 is heated by a heater (not shown), and as the liquid sample passes through the column 14 heated in the column oven 15 together with the mobile phase, the components in the liquid sample are separated over time.

[0015] The liquid sample that has passed through the column 14 is introduced into the ICP mass spectrometer 2 in a state in which each component in the liquid sample has been separated. That is, each component in the separated liquid sample is introduced sequentially from the liquid chromatograph 1 into the ICP mass spectrometer 2.

[0016] In this embodiment, a liquid sample contains multiple types of components that have the same element but different chemical forms. For example, when the target element to be analyzed is arsenic (As), its chemical form is roughly classified into inorganic arsenic compounds and organic arsenic compounds. Inorganic arsenic compounds include arsenous acid (As), which is a trivalent arsenic compound, and organic arsenic compounds. 3+ ) and arsenic acid (As 5+ ) are examples.

[0017] Organic arsenic compounds include arsenic metabolites and marine-derived arsenic compounds. Examples of arsenic metabolites include DMA (dimethylarsinic acid, a trivalent arsenic compound, or dimethylarsinic acid, a pentavalent arsenic compound) and MMA (monomethylarsonic acid, a trivalent arsenic compound, or monomethylarsonic acid, a pentavalent arsenic compound). Examples of marine-derived arsenic compounds include AB (arsenobetaine).

[0018] The ICP mass spectrometer 2 includes an internal standard element introducing section 3, an ICP section 4, an interface section 5, and an MS section 6. In this embodiment, by providing the internal standard element introducing section 3 in the piping connecting the liquid chromatograph 1 and the ICP mass spectrometer 2, it is possible to mix a solution of an internal standard element (internal standard solution) with the liquid sample introduced from the liquid chromatograph 1 into the ICP mass spectrometer 2.

[0019] The internal standard element introducing section 3 includes an internal standard solution reservoir 31, a second pump 32, and a mixer 33. An internal standard solution is stored in the internal standard solution reservoir 31. Examples of the internal standard element contained in the internal standard solution include, but are not limited to, gallium (Ga), selenium (Se), and tellurium (Te). It is preferable to use an element with no isotopes or an element with a large isotope ratio as the internal standard element.

[0020] In this embodiment, the target element is arsenic (As), and mass spectrometry is performed on a plurality of components of the target element with different chemical forms. Note that arsenic (As) in this case is a stable isotope of 75 In this case, it is preferable to select an element with a mass or ionization efficiency close to that of the target element, arsenic (As), as the internal standard element. When fluctuations within the plasma are large, an element with a similar ionization efficiency is preferable, and when fluctuations in the convergence of ions after passing through the plasma are large, it is preferable to select an element with a similar mass. It is a stable isotope 71When Ga is used as the internal standard element, the target element 75 This is preferable because its mass is close to that of As. It is also important that the internal standard element is not contained in the actual sample, or that its content is so small that it can be ignored compared to the amount added.

[0021] The internal standard solution in the internal standard solution reservoir 31 is pumped out by driving the second pump 32 and supplied to the mixer 33. The second pump 32 is a liquid-transfer pump configured, for example, as a tube pump. A tube pump is a pump that squeezes an elastic tube with a roller to push out the liquid in the tube, and is capable of delivering liquid at a constant flow rate with high precision. Thus, it is preferable to use a pump that can deliver liquid at a constant flow rate with high precision as the second pump 32.

[0022] The mixing section 33 is connected to a first pipe 331 communicating with the column 14 of the liquid chromatograph 1, a second pipe 332 communicating with the second pump 32, and a third pipe 333 communicating with the ICP section 4. The inner diameter of the third pipe 333 is the same as the inner diameters of the first pipe 331 and the second pipe 332. A T-shaped flow path is formed in the mixing section 33, and the liquid flowing in from the first pipe 331 and the liquid flowing in from the second pipe 332 are mixed in the mixing section 33, and the mixed liquid flows out from the third pipe 333.

[0023] According to the internal standard element introducing section 3 having such a configuration, the liquid sample introduced from the liquid chromatograph 1 into the ICP section 4 via the first pipe 331 and the third pipe 333 is mixed with the internal standard solution from the second pipe 332 at a constant flow rate without passing through the liquid chromatograph 1. This makes it possible to introduce a liquid sample (mixed liquid) containing an internal standard element into the ICP section 4. Note that the above-mentioned constant flow rate means that, for example, the set flow rate of the second pump 32 is constant, and the concept of a constant flow rate also includes cases where the actual flow rate fluctuates slightly.

[0024] The ICP unit 4 functions as an ion source that ionizes elements in a liquid sample using plasma generated by inductive coupling. The ICP unit 4 includes a nebulizer 41 and a plasma torch 42.

[0025] The nebulizer 41 atomizes the mixed liquid introduced from the mixer 33. As a result, the mixed liquid in a mist (aerosol) state is supplied to the plasma torch 42 together with a carrier gas. In addition to the mist mixed liquid, a plasma gas is also supplied to the plasma torch 42. The carrier gas and plasma gas are, for example, argon gas.

[0026] In the plasma torch 42, plasma is generated by ionizing the plasma gas with a high-frequency electromagnetic field generated by an induction coil (not shown). The atomized liquid mixture is sprayed into the plasma generated in this manner along with a carrier gas, ionizing the elements in the liquid mixture. The elements ionized in the ICP unit 4 are introduced into the MS unit 6 via the interface unit 5.

[0027] The interface section 5 is equipped with cones 51, which include, for example, a sampling cone and a skimmer cone. The cone 51 is a conical metal member having a minute hole (orifice) with an inner diameter of about several mm. The elements ionized in the ICP section 4 pass through the orifice of the cone 51 and are then introduced into the MS section 6.

[0028] The MS unit 6 includes, for example, an ion lens 61, a quadrupole mass spectrometer 62, and a detector 63 in a housing that is evacuated by a vacuum pump (not shown). A chromatogram can be obtained by performing mass analysis in the MS unit 6 on the ionized elements introduced from the ICP unit 4 through the interface unit 5 to the MS unit 6.

[0029] The ion lens 61 focuses the ionized elements that pass through the cone 51 and enter the MS section 6, and makes them enter the quadrupole mass spectrometer 62. The quadrupole mass spectrometer 62 is an example of a mass spectrometer, and separates the ions that enter from the ion lens 61 according to mass. However, the mass spectrometer is not limited to the quadrupole mass spectrometer 62, and other types of mass spectrometers, such as a double focusing type, may also be used. Furthermore, a magnetic field mass spectrometer or a time-of-flight mass spectrometer may also be used as the mass spectrometer.

[0030] The detector 63 detects ions separated by mass in the quadrupole mass spectrometer 62 and outputs a signal corresponding to the detected intensity. A chromatogram can be obtained based on the output signal from this detector 63. For example, by adding up the intensities of all ions detected over time, a total ion current (TIC) chromatogram can be obtained. Furthermore, by extracting only the intensities of specific masses detected over time, a mass chromatogram (MC) can be obtained.

[0031] 2. Electrical configuration of LC-ICP mass spectrometer 2 is a block diagram showing an example of the electrical configuration of an LC-ICP mass spectrometer. The operation of this LC-ICP mass spectrometer is controlled by a control unit 7, which is configured by a processor including, for example, a CPU (Central Processing Unit).

[0032] In addition to the control unit 7, the LC-ICP mass spectrometer also includes a storage unit 8 and a display unit 9 electrically connected to the control unit 7. The storage unit 8 includes, for example, a read-only memory (ROM), a random access memory (RAM), or a hard disk, and stores computer programs and other data necessary for control. The display unit 9 includes, for example, a liquid crystal display.

[0033] The control unit 7 functions as a liquid delivery control unit 71, a sample injection control unit 72, an ICP control unit 73, an MS control unit 74, a chromatogram acquisition processing unit 75, a correction processing unit 76, and a display processing unit 77, etc. The control unit 7 is electrically connected to the first pump 12, the second pump 32, the sample injection device 13, the ICP unit 4, the MS unit 6, etc.

[0034] The liquid supply control unit 71 controls the operation of the first pump 12 and the second pump 32. Specifically, the liquid supply control unit 71 controls the operation of the first pump 12 to control the flow rate of the mobile phase supplied from the mobile phase reservoir 11 to the column 14. In addition, the liquid supply control unit 71 controls the operation of the second pump 32 to control the flow rate of the internal standard solution supplied from the internal standard solution reservoir 31 to the mixer 33.

[0035] The sample injection control unit 72 controls the sample injection device 13 to inject the liquid sample at a predetermined timing into the mobile phase before it is supplied to the column 14. The injection timing of the liquid sample may be a fixed timing determined in advance, or may be a timing arbitrarily set by the user.

[0036] The ICP control unit 73 controls the operation of the ICP unit 4. Specifically, the ICP control unit 73 controls the power supply to the induction coil and also controls the supply of carrier gas and plasma gas, thereby controlling the generation of plasma.

[0037] The MS control unit 74 controls the operation of the MS unit 6. Specifically, the MS control unit 74 controls the operation of a vacuum pump to maintain the inside of the housing of the MS unit 6 in a vacuum state, and also controls the supply of electricity to each unit such as the quadrupole mass spectrometer 62.

[0038] An output signal from the detector 63 of the MS unit 6 is input to the control unit 7, and a chromatogram is acquired based on the output signal by the chromatogram acquisition processing unit 75. The chromatogram acquisition processing unit 75 includes a first chromatogram acquisition processing unit 751 and a second chromatogram acquisition processing unit 752.

[0039] The first chromatogram acquisition processing unit 751 acquires a first chromatogram 81 by mass spectrometry of each component in the liquid sample introduced from the liquid chromatograph 1 out of the mixed liquid introduced into the ICP unit 4. The first chromatogram 81 acquired by the first chromatogram acquisition processing unit 751 is stored in the memory unit 8.

[0040] Each component in the liquid sample is ionized into an element in the ICP unit 4, and mass spectrometry is performed in the MS unit 6. For example, arsenic (As), which is a different chemical form of arsenic, is ionized into an element in the ICP unit 4, and mass spectrometry is performed in the MS unit 6. 3+ ), arsenic acid (As 5+ When a liquid sample contains arsenic ions, which are ions of the same element obtained from each component in the ICP unit 4, the liquid sample is subjected to mass spectrometry in the MS unit 6.

[0041] In this way, even when ions of the same element are obtained from each component in the liquid sample in the ICP unit 4, the components are previously separated in time in the liquid chromatograph 1, and therefore peaks are detected at different retention times for each component (each chemical form) by mass analysis in the MS unit 6. This allows the first chromatogram acquisition processor 751 to acquire a TIC chromatogram including peaks for each chemical form as the first chromatogram 81.

[0042] The component corresponding to any one of the peaks included in the first chromatogram is an internal standard component for correcting the peaks of other components. For example, if arsenobetaine (AB) is used as the internal standard component, the height or area of ​​the peak can be used to correct the peak of arsenous acid (As). 3+ ), arsenic acid (As 5+The internal standard component has an element different from the internal standard element (e.g., gallium (Ga), selenium (Se), tellurium (Te), etc.) contained in the internal standard solution stored in the internal standard solution storage section 31.

[0043] The second chromatogram acquisition processor 752 acquires a second chromatogram 82 by mass spectrometry of the internal standard element introduced from the internal standard element introduction unit 3 in the mixed liquid introduced into the ICP unit 4. The second chromatogram 82 acquired by the second chromatogram acquisition processor 752 is stored in the memory unit 8.

[0044] For example, when the internal standard element contained in the internal standard solution is gallium (Ga), mass analysis is performed in the MS unit 6 on the gallium ions obtained in the ICP unit 4. Therefore, the second chromatogram acquisition processing unit 752 can acquire a mass chromatogram of gallium (Ga) as the second chromatogram 82 by extracting only the intensity of the mass corresponding to the gallium ions.

[0045] The correction processing unit 76 includes a first correction processing unit 761 and a second correction processing unit 762. The first correction processing unit 761 performs a calculation process to correct the first chromatogram 81 using the second chromatogram 82. Furthermore, the second correction processing unit 762 performs a calculation process to correct the peak of the target component included in the first chromatogram 81 corrected by the first correction processing unit 761 with the peak of the internal standard component included in the first chromatogram 81. Specific calculation processes performed by the first correction processing unit 761 and the second correction processing unit 762 will be described later.

[0046] The data of first chromatogram 81 after correction by first correction processing unit 761 and second correction processing unit 762 is stored in storage unit 8. Display processing unit 77 can read out the data of first chromatogram 81 after correction by first correction processing unit 761 and second correction processing unit 762 from storage unit 8 and display it on display unit 9. It is also possible to create a calibration curve using the data of first chromatogram 81 after correction.

[0047] 3. Specific examples of correction processing 3 and 4 are diagrams for explaining a specific example of the correction process. FIG. 3 is an example of a second chromatogram 82 obtained by mass spectrometry for gallium (Ga), which is an internal standard element. On the other hand, FIG. 4 is an example of a second chromatogram 82 obtained by mass spectrometry for arsenous acid (As 3+ ), arsenic acid (As 5+ 3. The figure shows the results of correcting a first chromatogram 81 obtained by mass spectrometry of a liquid sample containing the components DMA and arsenobetaine (AB) using a second chromatogram 82 of FIG.

[0048] In this embodiment, the internal standard element solution is mixed with the liquid sample at a constant flow rate, resulting in a second chromatogram 82 with a substantially constant intensity, as shown in Fig. 3. The first correction processing unit 761 corrects the first chromatogram 81 by dividing the intensity value at each time in the first chromatogram 81 by the intensity value corresponding to the same time in the second chromatogram 82. That is, for the intensity value (first intensity value) in the first chromatogram 81 and the intensity value (second intensity value) in the second chromatogram 82 at the same retention time, the first intensity value is divided by the second intensity value, thereby correcting the first chromatogram 81.

[0049] The chromatogram of FIG. 4, which is the result of correcting the first chromatogram 81 using the second chromatogram 82, shows arsenic acid (As 5+ ) peak P1, arsenous acid (As 3+The second correction processor 762 corrects the peaks P1, P2, and P3 of the target components contained in the first chromatogram 81 corrected by the first correction processor 761 shown in FIG. 4 with the peak P4 of the internal standard component contained in the first chromatogram 81.

[0050] Specifically, arsenic acid (As 5+ ) peak P1, arsenous acid (As 3+ The intensity values ​​(peak heights) of peak P2 of DMA and peak P3 of DMA are divided by the intensity value (peak height) of peak P4 of arsenobetaine (AB), an internal standard component. However, correction can also be performed using the peak area instead of the peak intensity value (peak height). That is, arsenic acid (As 5+ ) peak P1, arsenous acid (As 3+ The areas of peak P2 of DMA and peak P3 of DMA may be divided by the area of ​​peak P4 of the internal standard component arsenobetaine (AB).

[0051] In this example, the target component is arsenic acid (As 5+ ), arsenic acid (As 3+ ) and DMA, and the internal standard component is arsenobetaine (AB), but this is not limited to this. 5+ ), arsenic acid (As 3+ At least one of arsenobetaine (AB) and DMA may not be included, or other components may be included. The internal standard component may be a component other than arsenobetaine (AB).

[0052] 4. Mass spectrometry flow 5 is a flowchart illustrating the steps of mass analysis. When a user instructs the LC-ICP mass spectrometer to start mass analysis, first, the first pump 12 of the liquid chromatograph 1 is driven, thereby continuously introducing the mobile phase into the column 14 (step S101). The mobile phase that has passed through the column 14 is supplied to the mixer 33 of the ICP mass spectrometer 2.

[0053] Furthermore, the second pump 32 of the internal standard element introducing section 3 is driven, thereby continuously introducing the internal standard solution from the internal standard element introducing section 3 into the mixing section 33 (step S102: internal standard element introducing step). At this time, the internal standard solution is introduced into the mixing section 33 at a constant flow rate without passing through the liquid chromatograph 1.

[0054] In this state, the sample injector 13 is driven, thereby injecting the liquid sample into the mobile phase introduced into the column 14 (step S103). The liquid sample injected into the mobile phase passes through the column 14, during which the components in the liquid sample are separated, and then mixed with the internal standard solution in the mixer 33, and the mixture is introduced into the ICP unit 4 (step S104: sample introduction step).

[0055] In the ICP unit 4, the mixed liquid introduced from the mixer 33 is atomized by the nebulizer 41, and the atomized mixed liquid is sprayed into plasma, thereby ionizing the elements in the mixed liquid. The ionized elements are then introduced into the MS unit 6 via the interface unit 5, where mass analysis is performed (step S105).

[0056] By mass analysis in the MS unit 6, a first chromatogram 81 is obtained (step S106: first chromatogram obtaining step), and a second chromatogram 82 is obtained (step S107: second chromatogram obtaining step). That is, the first chromatogram 81 is obtained by mass analysis of each component in the liquid sample, and the second chromatogram 82 is obtained by mass analysis of the internal standard element.

[0057] Thereafter, a process of correcting the first chromatogram 81 is performed using the acquired second chromatogram 82 (step S108: first correction step). As a result, the correction process is performed using the second chromatogram 82 as exemplified in Fig. 3, and as a result, the corrected first chromatogram 81 as exemplified in Fig. 4 is obtained.

[0058] Furthermore, a process is performed in which the peak of the target component contained in the corrected first chromatogram 81 is corrected with the peak of the internal standard component contained in the first chromatogram 81 (step S109: second correction step). In the example of FIG. 4, arsenic acid (As 5+ ) peak P1, arsenous acid (As 3+ Peak P2 of DMA and peak P3 of DMA are corrected with peak P4 of arsenobetaine (AB), an internal standard component.

[0059] In this way, first chromatogram 81 is obtained, which has been subjected to both the first correction process and the second correction process. The corrected first chromatogram 81 is stored in memory unit 8, and may be displayed on display unit 9 as needed. Furthermore, a calibration curve may be created using the data of corrected first chromatogram 81 stored in memory unit 8.

[0060] 5. Variations In the above embodiment, the target element to be analyzed is arsenic (As), but the target element may be other elements such as mercury (Hg), selenium (Se), or chromium (Cr).

[0061] Furthermore, the number of internal standard elements is not limited to one, and may be multiple. For example, in addition to gallium (Ga), other elements such as selenium (Se) or tellurium (Te) may be mixed as internal standard elements into a liquid sample and mass spectrometry may be performed to obtain multiple second chromatograms 82, and the first chromatogram 81 may be corrected by selecting a second chromatogram 82 corresponding to any one of the internal standard elements.

[0062] 6. Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0063] (Item 1) A mass spectrometry method according to one embodiment includes: A sample introduction step of introducing a liquid sample into an ICP mass spectrometer via a liquid chromatograph; an internal standard element introducing step of introducing an internal standard element into the liquid sample introduced in the sample introducing step by mixing a solution of the internal standard element without passing through the liquid chromatograph; a first chromatogram acquisition step of acquiring a first chromatogram by mass spectrometry of each component in the liquid sample introduced in the sample introduction step; a second chromatogram acquisition step of acquiring a second chromatogram by mass spectrometry of the internal standard element introduced in the internal standard element introduction step; and a first correction step of correcting the first chromatogram using the second chromatogram.

[0064] According to the mass spectrometry method described in paragraph 1, a second chromatogram is obtained by mass spectrometry of an internal standard element mixed in a liquid sample, and the second chromatogram can be used to correct a first chromatogram obtained by mass spectrometry of each component in the liquid sample. This makes it possible to use the second chromatogram to correct measurement errors that occur when a target component in a liquid sample is affected by fluctuations in ionization efficiency in plasma or fluctuations in behavior in a mass spectrometer.

[0065] (Item 2) In the mass spectrometry method according to item 1, In the first correction step, the first chromatogram may be corrected by dividing an intensity value at each time in the first chromatogram by an intensity value corresponding to the same time in the second chromatogram.

[0066] According to the mass spectrometry method described in paragraph 2, measurement errors can be effectively corrected by correcting errors in intensity values ​​at each time in the first chromatogram using intensity values ​​corresponding to the same time in the second chromatogram.

[0067] (Item 3) In the mass spectrometry method according to item 1 or 2, the liquid sample introduced in the sample introduction step contains an internal standard component having an element different from the internal standard element; The method may further include a second correction step of correcting the peak of the target component contained in the first chromatogram corrected in the first correction step with the peak of the internal standard component contained in the first chromatogram.

[0068] According to the mass spectrometry method described in paragraph 3, after separating the chemical forms of the target component in the liquid sample using a liquid chromatograph, the peak of the target component contained in the first chromatogram can be corrected with the peak of the internal standard component contained in the first chromatogram, thereby making it possible to correct errors in the injection amount of the liquid sample into the liquid chromatograph.

[0069] (Item 4) In the mass spectrometry method according to item 3, In the second correction step, the peak of the target component may be corrected by dividing the intensity value or area of ​​the peak of the target component contained in the first chromatogram corrected in the first correction step by the intensity value or area of ​​the peak of the internal standard component contained in the first chromatogram.

[0070] According to the mass spectrometry method described in paragraph 4, the intensity value or area of ​​the peak of the target component contained in the first chromatogram is corrected using the intensity value or area of ​​the peak of the internal standard component contained in the first chromatogram, thereby making it possible to effectively correct measurement errors.

[0071] (Item 5) An ICP mass spectrometer according to one aspect includes: An ICP mass spectrometer into which a liquid sample is introduced via a liquid chromatograph, an internal standard element introducing unit that introduces an internal standard element into the liquid sample introduced from the liquid chromatograph by mixing a solution of the internal standard element without passing through the liquid chromatograph; a first chromatogram acquisition processing unit that acquires a first chromatogram by mass spectrometry of each component in the liquid sample introduced from the liquid chromatograph; a second chromatogram acquisition processing unit that acquires a second chromatogram by mass spectrometry of the internal standard element introduced from the internal standard element introduction unit; The system may further include a first correction processing unit that corrects the first chromatogram using the second chromatogram.

[0072] According to the ICP mass spectrometer described in paragraph 5, a second chromatogram can be obtained by mass spectrometry of an internal standard element mixed in a liquid sample, and the second chromatogram can be used to correct a first chromatogram obtained by mass spectrometry of each component in the liquid sample. This makes it possible to use the second chromatogram to correct measurement errors that occur when a target component in a liquid sample is affected by fluctuations in ionization efficiency in plasma or fluctuations in behavior in the mass spectrometer.

[0073] (Item 6) In the ICP mass spectrometer according to item 5, the liquid sample introduced from the liquid chromatograph contains an internal standard component having an element different from the internal standard element; The apparatus may further include a second correction processing unit that corrects the peak of the target component contained in the first chromatogram corrected by the first correction processing unit with the peak of the internal standard component contained in the first chromatogram.

[0074] According to the ICP mass spectrometer described in paragraph 6, after separating the chemical forms of the target component in the liquid sample using a liquid chromatograph, the peak of the target component contained in the first chromatogram can be corrected with the peak of the internal standard component contained in the first chromatogram, thereby making it possible to correct errors in the injection amount of the liquid sample into the liquid chromatograph. [Explanation of symbols]

[0075] 1 Liquid chromatograph 2 ICP mass spectrometer 3 Internal standard element introduction section 4 ICP section 5 Interface section 6 MS section 7 Control Unit 81 First chromatogram 82 Second chromatogram 751 First chromatogram acquisition processing unit 752 Second chromatogram acquisition processing unit 761 First correction processing unit 762 Second correction processing section P1~P4 peaks

Claims

1. A sample introduction step of introducing a liquid sample into an ICP mass spectrometer via a liquid chromatograph; an internal standard element introducing step of introducing an internal standard element into the liquid sample introduced in the sample introducing step by mixing a solution of the internal standard element without passing through the liquid chromatograph; a first chromatogram acquisition step of acquiring a first chromatogram by mass spectrometry of each component in the liquid sample introduced in the sample introduction step; a second chromatogram acquisition step of acquiring a second chromatogram by mass spectrometry of the internal standard element introduced in the internal standard element introduction step; a first correction step of correcting the first chromatogram using the second chromatogram; In the internal standard element introducing step, a solution of the internal standard element is mixed with the liquid sample at a constant flow rate while the liquid sample flows through a flow path connecting the liquid chromatograph and the ICP mass spectrometer.

2. 2. The mass analysis method according to claim 1, wherein in the first correction step, the first chromatogram is corrected by dividing the intensity value at each time in the first chromatogram by the intensity value corresponding to the same time in the second chromatogram.

3. the liquid sample introduced in the sample introduction step contains an internal standard component having an element different from the internal standard element; 3. The mass spectrometry method according to claim 1, further comprising a second correction step of correcting a peak of a target component contained in the first chromatogram corrected by the first correction step with a peak of an internal standard component contained in the first chromatogram.

4. 4. The mass spectrometry method according to claim 3, wherein the second correction step corrects the peak of the target component by dividing the intensity value or area of ​​the peak of the target component included in the first chromatogram corrected in the first correction step by the intensity value or area of ​​the peak of the internal standard component included in the first chromatogram.

5. An ICP mass spectrometer into which a liquid sample is introduced via a liquid chromatograph, an internal standard element introducing unit that introduces an internal standard element into the liquid sample introduced from the liquid chromatograph by mixing a solution of the internal standard element without passing through the liquid chromatograph; a first chromatogram acquisition processing unit that acquires a first chromatogram by mass spectrometry of each component in the liquid sample introduced from the liquid chromatograph; a second chromatogram acquisition processing unit that acquires a second chromatogram by mass spectrometry of the internal standard element introduced from the internal standard element introduction unit; a first correction processing unit that corrects the first chromatogram using the second chromatogram, In the internal standard element introduction section, a solution of an internal standard element is mixed with the liquid sample at a constant flow rate while the liquid sample flows through a flow path connecting the liquid chromatograph and the ICP mass spectrometer.

6. the liquid sample introduced from the liquid chromatograph contains an internal standard component having an element different from the internal standard element; 6. The ICP mass spectrometer according to claim 5, further comprising a second correction processing unit that corrects the peak of the target component included in the first chromatogram corrected by the first correction processing unit with the peak of the internal standard component included in the first chromatogram.

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