JP2013195115A - Mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid performing intensive MSanalyses on exclusively specific wells of high contents and acquire MSspectra in high sensitivity and high S/N if a plurality of mixed components are distributed in a plurality of wells.SOLUTION: MS spectrum acquisitions are performed on M wells in which mixed components are distributed, and peaks corresponding to respective components are extracted (S1-S3). If N is M or smaller, N wells containing the highest total amounts of ions are selected from the M wells and the peaks are assigned in ascending order of intensity to wells containing high total amounts of ions (S4-S6). If N is larger than M, an assignment is determined so that the lowest-intensity peak is assigned to a well containing the highest total amount of ions, and peaks are assigned in ascending order of peak intensity to wells of the same total amount of ions or less (S11-S13). Therefore, MSanalyses of the plurality of components are performed dispersedly on the plurality of wells.

Description

The present invention relates to a mass spectrometer for mass-analyzing a sample prepared by separating components by a liquid chromatograph or the like and spotting on a sample plate or the like, and more specifically, a specific mass-to-charge ratio derived from a sample component. The present invention relates to an MS ^n- type mass spectrometer capable of performing MS ⁿ analysis (n is an integer of 2 or more) on ions having s.

In the field of proteomics such as comprehensive analysis of proteins, LC / MALDI-MS, which connects a liquid chromatograph (LC) and a matrix-assisted laser desorption / ionization (MALDI) mass spectrometer offline. A configuration is often used. In offline LC / MALDI-MS, the sample solution separated in the liquid chromatographic column is fractionated according to the elution time sequence, mixed with the MALDI matrix using a spotting device, and then separated into different wells on the sample plate. Spot (see Non-Patent Document 1). A sample plate on which a large number of samples are prepared is set in a MALDI mass spectrometer, and mass spectrometry (hereinafter referred to as MS spectrum) or MS ⁿ spectrum is obtained by sequentially performing mass analysis on each sample, and the MS The target component is identified by processing the spectrum or the MS ⁿ spectrum by a technique such as database search.

  When performing a comprehensive analysis of the contained components, it is necessary to prepare a sample by separating various components mixed in the eluate from the column outlet without omission. Therefore, in the spotting device, fractionation is performed in which the eluate is dispensed into different wells for every fixed amount (or a fixed time corresponding to the amount). In such fractionation, when the sample holding time width in the column exceeds the spotting time interval, as shown in FIG. 3, a component (one component or a plurality of mixed components) corresponding to one peak on the chromatogram is obtained. Spotting is performed while being distributed in a plurality of wells. In the example of FIG. 3, a component formed in three wells (i), (ii), and (iii) includes a component corresponding to one peak.

In general, when performing MS ² analysis automatically in LC / MALDI-MS, in order to improve throughput and detection sensitivity, a normal operation without ion dissociation such as collision-induced dissociation (CID) is required. Referring to the MS spectrum obtained by mass spectrometry, select the well having the highest ion content (the ion intensity is the maximum) from a plurality of consecutive wells in which the same component is dispersed. To perform MS ² analysis.

For example, when component separation on a column is appropriately performed and one peak corresponds to only one component, one clear peak derived from the component appears in the MS spectrum. Therefore, a well having the maximum signal intensity in the mass-to-charge ratio of the peak is selected, and MS ² analysis is performed using the peak as a precursor ion for the well.

On the other hand, when a sample contains a plurality of components having substantially the same retention time, the plurality of components are eluted in a mixed state without being separated by the column. Therefore, the plurality of components are observed as one peak on the chromatogram and spotted on a plurality of continuous wells in a state in which the quantity ratio of each component is substantially maintained. When mass spectrometry is performed on the sample prepared in this manner, peaks appear at different mass-to-charge ratios for each component on the MS spectrum. In the example of FIG. 3, three components are mixed, and three clear peaks a, b, and c corresponding to each component appear in the MS spectrum. When performing MS ² analysis, select the well with the highest ion content (the signal intensity is the maximum) for each component from the dispersed and spotted wells. MS ² analysis is performed using the derived peak as a precursor ion.

As described above, among the components contained in the sample solution, when the retention times of the plurality of components are substantially the same, the amount ratio of each component in the plurality of wells is substantially maintained. Therefore, as shown in FIG. 3, the same well has the maximum signal intensity of peaks a, b, and c corresponding to the three components on the MS spectrum. Therefore, MS ² analysis using well (ii) is performed for all three components. In addition, in a MALDI ion source, a sufficient amount of ions are not always generated by a single laser irradiation, so that a plurality of laser irradiations are performed in order to obtain a mass analysis result for a certain component. Generally, the obtained ionic strength is integrated. If for the same well and trying to run multiple more components of MS ² analysis each time, the number of consumption of the sample, would then samples depleted during the first half of the MS ² analysis, significant in the latter half of the MS ² during analysis Data may not be available.

When the sample to be analyzed is depleted as described above, good or high-sensitivity MS ² spectrum cannot be obtained for some or all components. For example, component identification using this MS ² spectrum When performing the above, the identification accuracy is lowered. Even when there is a risk of sample depletion as described above, in the conventional mass spectrometer, wells that were not selected will be discarded without being subjected to MS ² analysis, and are contained in the wells. The sample components are completely wasted.

Iwata and others, “Proteomics offline analysis using multi-dimensional LC / MALDI-TOF MS with high-throughput spotting device”, Shimazu review, Shimazu review editorial department, October 30, 2004, volume 61, 1・ No. 2, p. 49-61

The present invention has been made in view of the above problems, and its object is to effectively use a sample when performing MS ⁿ analysis on a plurality of components dispersed in a plurality of wells. To provide a mass spectrometer capable of performing MS ⁿ analysis with high S / N and high sensitivity for each component.

In order to solve the above problems, the present invention provides a mass for performing MS ⁿ analysis (n is an integer of 2 or more) on a plurality of samples prepared by fractionating samples separated by chromatography. An analysis apparatus that performs MS ⁿ analysis on a sample in which a plurality of components that have not been separated by chromatography are included in M samples (M is an integer of 2 or more) that are continuous in time In the mass spectrometer,
a) MS spectrum acquisition means for acquiring an MS spectrum by performing mass spectrometry without dissociation operation on at least one of the M samples;
b) peak extraction means for extracting peaks derived from a plurality of components contained in the M samples based on at least one MS spectrum obtained by the MS spectrum acquisition means;
c) assigning the sample having the maximum total ion amount among the M samples to the peak having the smallest intensity among the plurality of peaks extracted by the peak extracting means, and Among the M samples, the sample having the smallest total ion content is assigned to the peak with the highest intensity, and the intensity is the lowest among the extracted peaks. For the peaks other than the peak that is the largest, the intensity of each peak and the total ion amount of each sample are assigned so that the samples having the same or decreased total ion amount among the M samples are assigned in order of increasing intensity. A sample assignment processing means for determining a sample to be subjected to MS ⁿ analysis using each peak as a precursor ion based on
d) MS ⁿ analysis in which any one of the plurality of peaks is set as a precursor ion for any of the M samples for each of the plurality of components according to the assignment determined by the sample assignment processing means. and MS ⁿ spectra acquisition means for acquiring MS ⁿ spectra run,
It is characterized by having.

  In the mass spectrometer according to the present invention, “chromatography” is typically liquid chromatography or capillary electrophoresis. When the mass spectrometer is equipped with an ion source such as a MALDI ion source or an LDI (= Laser Desorption / Ionization) ion source, a “sample” is formed in each well on the sample plate. It is a sample.

In the mass spectrometer according to the present invention, when determining samples for performing MS ⁿ analysis using peaks derived from different components as precursor ions, the magnitude relationship of the intensity of each peak for a plurality of components is used for sample selection. . In consecutive M samples including a plurality of components that are not separated by chromatography, the absolute value of the content varies from sample to sample, but the amount ratio of the plurality of components is assumed to be substantially constant. Therefore, in a sample of M samples (usually the sample corresponding to the position of the peak top on the chromatogram), a component having a relatively high content, that is, a peak showing high intensity on the MS spectrum. The corresponding component should have a relatively high content in other samples in the M samples as compared to the other components. On the contrary, a component having a relatively low content in a certain sample among M samples, that is, a component corresponding to a peak showing a low intensity on the MS spectrum, is the other sample in the M samples. In addition, the content should be relatively low compared to other components. For this reason, a component having a relatively high content among a plurality of mixed components does not necessarily need to be subjected to MS ⁿ analysis on a sample having the maximum content. An MS ⁿ spectrum is obtained. On the other hand, for a component having a relatively small content among a plurality of mixed components, the absolute value of the content should be relatively small even if the sample has the largest content. In order to obtain a good MS ⁿ spectrum, it is necessary to preferentially assign samples with as much content as possible.

  Therefore, in order to preferentially assign a sample with a high content to a component with a low content, the sample assignment processing means has M samples for the peak having the smallest intensity among the plurality of extracted peaks. A sample having the maximum total ion amount is assigned, and any of the M samples having the maximum total ion amount is not the maximum for the peak having the maximum intensity among the plurality of extracted peaks. And for the peaks other than the peak having the minimum and maximum intensities among the extracted peaks, the total ion amount is the same or decreases in the M samples in order of increasing intensity. Assign a sample.

Here, the sample having the same total ion amount in the M samples may be a separate sample having the same total ion amount in the M samples. The same sample may be used among the samples. That is, a plurality of peaks may be associated with the same sample, that is, a plurality of MS ⁿ analyzes may be performed in which different precursor ions are set for the same sample. However, in the mass spectrometer according to the present invention, as in the prior art, MS ⁿ analysis cannot be performed on the same sample for all of a plurality of mixed components, and at least for two samples. MS ⁿ analysis will be performed. In other words, the sample for which the MS ⁿ analysis is performed is not shifted to one, and the MS ⁿ analysis dispersed in at least two or more samples is performed.

  In the mass spectrometer according to the present invention, preferably, when the number N of peaks extracted by the peak extraction means is M or less, the sample assignment processing means has a large total ion amount from M samples. It is preferable that N samples are selected in order, and a sample having a large total ion amount among N samples is assigned in a one-to-one order from the peak having the smallest intensity among the N peaks. .

According to this configuration, when the number of mixed components is less than or equal to the number M of samples, only MS ⁿ analysis for one component is performed for one sample, and there is almost no problem of sample depletion. Does not occur.

  In the mass spectrometer according to the present invention, when the number N of peaks extracted by the peak extraction unit is a multiple of M, the sample allocation processing unit starts from the peak having the smallest intensity among the N peaks. It is preferable that N / M pairs are arranged in order of increasing intensity, and a sample having a large total ion amount among the M samples is assigned on a one-to-one basis.

According to this configuration, when the number of mixed components is twice the number M of samples, the sample on which MS ⁿ analysis is performed is allocated in a well-balanced manner, and there is almost no problem of sample depletion. Absent.

According to the mass spectrometer of the present invention, when a plurality of components are mixed and dispersed in a plurality of samples, only a specific sample having the maximum content is concentrated on the MS ⁿ for each component. without analysis is performed, MS ⁿ analysis, that is, MS ⁿ spectra of S / n and the sensitivity of the MS ⁿ analysis executed in a state that allows sufficient samples are dispersed. Thereby, it is possible to prevent the sample from being exhausted even during the repeated analysis for the purpose of data integration and the like, and it is possible to avoid problems in the analysis result due to the sample exhaustion. In addition, effective use of a sample that has not been conventionally used leads to an improvement in analysis sensitivity.

The schematic block diagram of LC / MALDI-IT-TOFMS by one Example of this invention. Flowchart illustrating a processing procedure of the MS ² analysis in LC / MALDI-IT-TOFMS of the present embodiment. Explanatory view showing a problem of the MS ² analysis in the conventional LC / MALDI-IT-TOFMS.

  Hereinafter, an LC / MALDI-IT-TOFMS (liquid chromatograph / matrix-assisted laser desorption / ionization ion trap time-of-flight mass spectrometer) which is an embodiment of a mass spectrometer according to the present invention will be described with reference to the accompanying drawings. explain. FIG. 1 is a schematic configuration diagram of the LC / MALDI-IT-TOFMS of this embodiment.

The LC / MALDI-IT-TOFMS of this embodiment sorts and fractionates the LC unit 1 that separates various components in the liquid sample according to the holding time, and the sample containing the components separated by the LC unit 1. A spotting device 2 that prepares a fraction sample (sample) by dispensing into different wells on the sample plate, and if there are multiple sample plates to be analyzed, one of them is selected. A sample transport unit 3 that transports one sample plate onto a stage of an MS unit 4 to be described later, and an MS unit 4 that performs mass analysis (MS analysis and MS ⁿ analysis in which n is 2 or more) on the sample; A data processing unit 5 that processes data obtained by the MS unit 4 and an analysis control unit 6 that controls the operation of each unit such as the LC unit 1 and the spotting device 2 are provided.

  The LC unit 1 is introduced on the mobile phase, the mobile phase container 11 in which the mobile phase is stored, the liquid feeding pump 12 that sucks the mobile phase and sends it at a constant flow rate, the injector 13 that injects the sample into the mobile phase, and the mobile phase. A column 14 that separates various components in the sample in the time direction, and a detector 15 such as an absorption detector that sequentially detects components contained in the eluate from the column 14. The detector 15 does not disturb the flow of the eluate, and various components contained in the eluate coming out of the LC unit 1 change with time.

  The spotting device 2 fractionates the eluate at a predetermined time interval, mixes the collected eluate with a predetermined amount of a MALDI matrix, and sequentially drops it into different wells 22 formed on the sample plate 21. A sample is prepared in each well 22. In other words, the sample formed in each well 22 includes one or more components that sequentially have different holding times, more strictly speaking, the holding time in the column 14 falls within a certain holding time range. Of course, as described above, there is a range of time for a certain component to elute in the eluate, and when the fractionation time interval is narrower than this range, one component (or the retention time is almost equal). A mixture of components that is the same) is contained in a sample in a plurality of wells 22 that are continuous in time.

The MS unit 4 includes a MALDI ion source including a laser light source unit 42 that irradiates a sample plate on the stage 41 with a laser beam, a function of holding ions inside and separating ions according to the mass-to-charge ratio m / z and collision An ion trap 43 having a function of dissociating ions by induced dissociation (CID), a time-of-flight mass analyzer 44 that separates various ions emitted from the ion trap 43 according to a mass-to-charge ratio, and sequentially detecting the separated ions MALDI-IT-TOFMS that includes a detector 45 that performs detection, and can perform not only MS analysis but also MS ⁿ analysis in which ion selection and ion dissociation are repeated one or more times.

The data processing unit 5 includes a chromatogram data collection unit 51 that stores the chromatogram data obtained by the detector 15 of the LC unit 1 in association with the sample plate number, the position information of each sample on the sample plate, and the like. MS spectrum data collection unit 52 and MS ² spectrum data collection unit 53 for storing MS spectrum data and MS ² spectrum data obtained by detector 45 of MS unit 4 respectively, and precursor ions for MS ² analysis based on the MS spectrum The function block includes a precursor ion extraction unit 54 for extraction, and a well / precursor ion assignment processing unit 55 that executes a characteristic process as described later to determine a well to be subjected to MS ² analysis.

  The data processing unit 5 and the analysis control unit 6 use, for example, a personal computer as a hardware resource, and execute the dedicated control / processing software installed in the personal computer, thereby realizing the above functional blocks. Can be configured.

In the LC / MALDI-IT-TOFMS having the above-described configuration, the sample plate on which a large number of samples are mounted in the spotting apparatus 2 is set on the stage 41 of the MS unit 4 by the sample transport unit 3 as described above. In order to comprehensively identify various components contained in the original sample, the MS unit 4 performs MS analysis and MS ⁿ analysis on the sample formed in the well on the sample plate. Processing and control at that time The operation is performed as follows.
FIG. 2 is a flowchart showing an operation procedure of this comprehensive identification process and control.

  In the data processing unit 5, the chromatogram data collection unit 51 stores the chromatogram for the sample, the time on the chromatogram, and the position information of the well on the sample plate (that is, the position information of the sample) in association with each other. Yes. Therefore, the position of the sample corresponding to one peak period (a period from the peak start point to the peak end point) on the chromatogram is known. Therefore, based on the information stored in the chromatogram data collection unit 51, the data processing unit 5 identifies a well containing one or more components corresponding to a certain peak on the chromatogram, The number M of wells is obtained (step S1). The peaks to be processed may be automatically and sequentially specified on the chromatogram, or may be manually specified by the user from an input unit (not shown).

  When a well containing one or more components corresponding to one peak is identified, the position information of the M wells (and information for identifying the sample plate when the sample plate itself needs to be replaced) Is sent to the analysis control unit 6. Under the control of the analysis control unit 6, the MS unit 4 performs MS analysis on the designated M wells, and the MS spectrum data collection unit 52 acquires MS spectrum data (step S2). As a result, for example, an MS spectrum as shown in FIG. 3 is obtained. As described above, FIG. 3 is an example in which three components have substantially the same retention time and are observed as one peak without component separation. In such a case, three peaks a, b, and c corresponding to the three components appear in each MS spectrum for three wells that are temporally continuous, and the intensity ratios of these peaks are substantially equal.

  Next, the precursor ion extraction unit 54 performs peak picking on the integrated MS spectrum created by integrating, for example, the MS spectrum for the well having the maximum total ion amount or the MS spectrum obtained for all the wells, Peaks corresponding to each component are extracted (step S3). Here, it is assumed that the number of mixed components is N and N peaks are extracted. Of course, by performing data processing such as appropriate noise removal and background removal before peak picking, noise unrelated to the analysis target component contained in the sample can be removed. Therefore, when N peaks are extracted from the MS spectrum, it is possible to estimate with high accuracy that the number of mixed components is N.

  Next, the well / precursor ion assignment processing unit 55 determines whether or not the number of wells M is equal to or greater than the number of peaks N (step S4). If the determination is Yes, the process proceeds to step S5, where N wells are selected in descending order of the total ion amount independent of the mass-to-charge ratio among the M wells. That is, the same number of wells as the number of peaks N are selected. Of course, when N = M, there is no room for selection, and all M wells are designated. Then, the N ions are assigned one-to-one to the wells with the large total ion amount in order from the peak with the lowest ion intensity (step S6).

  As an example, consider a case where the number of peaks N = 4 and the number of wells M = 6. The peak intensity of the four peaks a, b, c, d is d> c> b> a, and the total ion amount of the six wells A, B, C, D, E, F is A> B> C It is assumed that> D> E> F. In this case, it is determined Yes in step S4, and in step S5, four wells having a large total ion amount, that is, A, B, C, and D are selected from the six wells. Then, by the processing in step S6, the peaks assigned to each well are changed from peak a → well A, peak b → well B, peak c → well C, peak d → well D.

If the assignment of peaks, ie, precursor ions and wells, is determined as described above, this result is given to the analysis control unit 6, and under the control of the analysis control unit 6, the MS unit 4 assigns N wells. On the other hand, MS ² analysis is performed using the peaks assigned one by one as precursor ions (step S7). In the MS ² analysis, for example, ions obtained by repeating laser irradiation to the same well several times are once trapped in the ion trap 43, then the ions are cleaved by CID, and a large amount of product ions generated by the cleavage May be introduced into the time-of-flight mass analyzer 44 for mass analysis. The MS ² spectrum data obtained by such MS ² analysis is stored in the MS ² spectrum data collecting unit 53, and an identification processing unit (not shown) performs a database search or a de novo sequence search using the MS ² spectrum, and thereby a peptide or the like. Are identified (step S8).

  On the other hand, if it is determined No in step S4, the process proceeds to step S11, and the well / precursor ion assignment processing unit 55 first calculates N / M. Then, an integer value α obtained by rounding up the decimal point of the calculated value and an integer value β (= α−1) obtained by subtracting 1 from α are calculated.

Next, x is the number of wells that perform MS ² analysis on α peaks and y is the number of wells that perform MS ² analysis on β peaks, and solves the following simultaneous equations (1) ( Step S12).
x + y = M
αx + βy = N (1)

If x and y are obtained based on the values of N, M, α, and β, then β of the N peaks from the peak with the lowest ionic strength, in order from the well with the highest total ion content. Assign to y wells. This determines the allocation of β × y peaks among the N peaks. After that, the remaining peaks (N-β · y) are assigned to x wells in order from the well with the largest total ion content, α in order from the peak with the lowest ion intensity. As a result, the assignment of wells to be subjected to MS ² analysis is determined for all N peaks (step S13).

The assigning process in steps S11 to S13 described above is a precursor selected from one well in order to prioritize MS ² analysis of a peak having a low peak intensity, except when the number of peaks N is a multiple of the number of wells M. This means that the number of ion candidates is always reduced by one for the number of peaks with low intensity compared to the number of peaks with high peak intensity.

Here, some specific examples in the case where the peak number N and the number of wells M of the precursor ion are specifically given will be given.
[Example 1] When the number of peaks N = 4 and the number of wells M = 3 The peak intensity of the four peaks a, b, c, d is d>c>b> a, and the three wells A, B , C total ion amount is A>B> C. In this case, it is determined No in step S4, and in step S11, since N / M = 4/3 = 1.33, α = 2 and β = 1 are calculated. Solving the simultaneous equations (1) from N = 4, M = 3, α = 2, and β = 1 yields x = 1 and y = 2. By the processing in step S13, the peaks assigned to each well are changed from peak a → well A, peak b → well B, peak c, d → well C.

[Example 2] When the number of peaks N = 5 and the number of wells M = 3 The peak intensities of the five peaks a, b, c, d, e are e>d>c>b> a, Assume that the total amount of ions in the wells A, B, and C is A>B> C. In this case, it is determined No in step S4, and in step S11, N / M = 5/3 = 1.67, so α = 2 and β = 1 are calculated. Solving the simultaneous equations (1) from N = 5, M = 3, α = 2, and β = 1 yields x = 2 and y = 1. By the processing in step S13, the peaks assigned to each well are changed from peak a → well A, peak b, c → well B, peak d, e → well C.

[Example 3] When the number of peaks N = 6 and the number of wells M = 3 The peak intensities of the six peaks a, b, c, d, e, and f are f>e>d>c>b> a It is assumed that the total amount of ions in the three wells A, B, and C is A>B> C. In this case, it is determined No in step S4, and in step S11, since N / M = 6/3 = 2, α = 2 and β = 1 are calculated. Solving the simultaneous equations (1) from N = 6, M = 3, α = 2, and β = 1 yields x = 2 and y = 0. By the processing in step S13, the peaks assigned to each well are changed from peak a, b → well A, peak c, d → well B, peak e, f → well C.

  Thus, when the number of peaks N is a multiple of the number of wells M, the same number of peaks are assigned to each well. For example, when the number of peaks N = 9 and the number of wells M = 3, 9/3 = 3 are assigned to the wells with the larger total ion amount in order from the peak with the lowest ion intensity. When the number of peaks N = 8 and the number of wells M = 4, 8/4 = 2 are assigned to the wells with the larger total ion amount in order from the peak with the lowest ion intensity.

However, in this case, in order to give priority to MS ² analysis of a peak having a low peak intensity, the assignment may be changed as follows. That is, when the number of peaks N = 6 and the number of wells M = 3, the peak a → well A, peak b, c → well B, peak d, e, f → well C can be set. When the number of peaks N = 9 and the number of wells M = 3, peak a, b → well A, peak c, d, e → well B, peak f, g, h, i → well C Can do. Further, when the number of peaks N = 8 and the number of wells M = 4, peak a → well A, peak b, c → well B, peak d, e → well C, peak f, g, h → well D , And can be.

[Example 4] When the number of peaks N = 8 and the number of wells M = 3 The peak intensities of the eight peaks a, b, c, d, e, f, g, h are h>g>f>e> d >C>b> a, and the total amount of ions in the three wells A, B, and C is A>B> C. In this case, it is determined No in step S4, and in step S11, since N / M = 8/3 = 2.67, α = 3 and β = 2 are calculated. Solving the simultaneous equations (1) from N = 8, M = 3, α = 3, and β = 2 yields x = 2 and y = 1. By the processing in step S13, the peaks assigned to each well are changed from peak a, b → well A, peak c, d, e → well B, peak f, g, h → well C.

[Example 5] When the number of peaks N = 9 and the number of wells M = 4 The peak intensities of the nine peaks a, b, c, d, e, f, g, h, i are i>h>g> f >E>d>c>b> a, and the total amount of ions in the four wells A, B, C, and D is A>B>C> D. In this case, it is determined No in step S4, and in step S11, N / M = 9/4 = 2.25, so α = 3 and β = 2 are calculated. Solving the simultaneous equations (1) from N = 9, M = 4, α = 3, and β = 2 yields x = 1 and y = 3. By the processing in step S13, the peaks assigned to each well are changed from peak a, b → well A, peak c, d → well B, peak e, f → well C, peak g, h, i → well D. .

  In reality, since the number of wells M is in the range of 3 to 4 and the number of peaks N is in the range of about 1 to 9, only the above example is given. It can be easily understood that the assignment can be appropriately determined.

If the assignment of peaks, ie, precursor ions and wells, is determined as described above, the result is given to the analysis control unit 6, and under the control of the analysis control unit 6, the MS unit 4 MS ² analysis is performed using two or more wells of which one or more assigned peaks are precursor ions (step S14). Thereafter, the process proceeds to step S8 described above, and the MS ² spectrum data obtained by the MS ² analysis is stored in the MS ² spectrum data collection unit 53, and the identification processing unit (not shown) performs database search or de novo sequence using the MS ² spectrum. A target component such as a peptide is identified by searching or the like.

As described above, according to the LC / MALDI-IT-TOFMS of the present example, the M wells corresponding to one peak on the chromatogram are concentrated on one specific well. without performing the MS ² analysis for each component, the total ion content is MS ² analysis was appropriately dispersed by using also another well not maximum is performed. Thereby, it is possible to prevent sample depletion due to intensive MS ² analysis of only a specific well, and therefore, a high sensitivity, high S / N MS ² spectrum can be obtained.

In the above embodiment, the case where the MS ² analysis is performed has been described. However, it is natural that the above method can be applied to the case where the assignment of the precursor ion and the sample is determined when the MS ⁿ analysis in which n is 3 or more is executed. .

  Moreover, since the said Example is only an example of this invention, even if it carries out a deformation | transformation, correction, addition, etc. suitably in the range of the meaning of this invention, it is natural that it is included in the claim of this application.

DESCRIPTION OF SYMBOLS 1 ... LC part 11 ... Mobile phase container 12 ... Liquid feed pump 13 ... Injector 14 ... Column 15 ... Detector 2 ... Spotting device 21 ... Sample plate 22 ... Well 3 ... Sample conveyance part 4 ... MS part 41 ... Stage 42 ... Laser Light source 43 ... Ion trap 44 ... Time-of-flight mass analyzer 45 ... Detector 5 ... Data processing unit 51 ... Chromatogram data collection unit 52 ... MS spectrum data collection unit 53 ... MS ² spectrum data collection unit 54 ... Precursor ion extraction 55: Well / precursor ion allocation processing unit 6: Analysis control unit

Claims (3)

A mass spectrometer that performs MS ⁿ analysis (n is an integer of 2 or more) on a plurality of samples prepared by fractionating a sample separated by chromatography, and a plurality of components not separated by chromatography In a mass spectrometer that performs MS ⁿ analysis on a sample in a state where the components are contained in M samples (M is an integer of 2 or more) that are continuous in time,
a) MS spectrum acquisition means for acquiring an MS spectrum by performing mass spectrometry without dissociation operation on at least one of the M samples;
b) peak extraction means for extracting peaks derived from a plurality of components contained in the M samples based on at least one MS spectrum obtained by the MS spectrum acquisition means;
c) assigning the sample having the maximum total ion amount among the M samples to the peak having the smallest intensity among the plurality of peaks extracted by the peak extracting means, and Among the M samples, the sample having the smallest total ion content is assigned to the peak with the highest intensity, and the intensity is the lowest among the extracted peaks. For the peaks other than the peak that is the largest, the intensity of each peak and the total ion amount of each sample are assigned so that the samples having the same or decreased total ion amount among the M samples are assigned in order of increasing intensity. A sample assignment processing means for determining a sample to be subjected to MS ⁿ analysis using each peak as a precursor ion based on
d) MS ⁿ analysis in which any one of the plurality of peaks is set as a precursor ion for any of the M samples for each of the plurality of components according to the assignment determined by the sample assignment processing means. and MS ⁿ spectra acquisition means for acquiring MS ⁿ spectra run,
A mass spectrometer comprising: The mass spectrometer according to claim 1,
When the number N of peaks extracted by the peak extraction means is M or less, the sample assignment processing means selects N samples from the M samples in descending order of the total ion amount, A mass spectrometer characterized by assigning samples having a large total ion amount in a one-to-one relationship among N samples in order of increasing intensity from a peak having the smallest intensity. The mass spectrometer according to claim 1,
When the number N of peaks extracted by the peak extraction means is a multiple of M, the sample assignment processing means performs N / M pieces in order of increasing intensity from the peak having the smallest intensity among the N peaks. A mass spectrometer characterized in that a sample having a large total ion amount among M samples is assigned one by one and assigned one by one.

Images