Chromatography mass spectrometer and chromatography mass analysis data processing method

Abstract

A chromatograph mass spectrometry device according to one aspect of the present invention is a device equipped with a data processing unit (3) for processing data collected by means of chromatograph mass spectrometry, wherein the data processing unit comprises: a first peak detecting unit (310, 311) for creating a chromatogram that reflects signal strengths at a plurality of m / z values, on the basis of the collected data, and performing peak detection with respect to the chromatogram; an extracted ion chromatogram (EIC) creating unit (313) for creating an EIC for the m / z of a centroid peak observed in a mass spectrum obtained in a time range of a detected peak, for at least some of the detected peaks; a second peak detecting unit (314) for performing peak detection with respect to the created EICs to acquire a peak top holding time for each detected peak; a grouping unit (315) for classifying the detected peaks into those having essentially the same peak top holding time; and a selecting unit (316) for selecting one or more representative m / z values or EICs corresponding to the m / z, for each group.

Description

[Technical field]

[0001] The present invention relates to a chromatograph mass spectrometer including a liquid chromatograph mass spectrometer and a gas chromatograph mass spectrometer, and to a chromatograph mass analysis data processing method. [Background technology]

[0002] In recent years, chromatograph mass spectrometers such as liquid chromatograph mass spectrometers (LC-MS) and gas chromatograph mass spectrometers (GC-MS) have been widely used to comprehensively analyze a large number of compounds contained in a sample. In general, when performing quantitative analysis using a chromatograph mass spectrometer, an extracted ion chromatogram (EIC) is created that shows the relationship between the ion intensity and retention time of the mass-to-charge ratio (strictly speaking, it is m / z in italics, but in this specification it is written as "mass-to-charge ratio" or "m / z") corresponding to the target compound to be quantified, and the area or height of the peak appearing in the chromatogram is compared with a calibration curve to calculate a quantitative value.

[0003] When quantifying only predetermined target compounds, the user specifies the m / z value corresponding to each target compound, and an EIC at the specified m / z value is created. However, the peak of the EIC obtained in this way may overlap with a peak derived from another compound that has the same (or very close) m / z value as the target compound, or the peak itself may actually be a peak derived from another compound rather than the target compound. For example, a method described in Patent Document 1 is a technique for identifying peaks affected by such impurities.

[0004] In the method described in the document, EICs are prepared for each of a plurality of m / z values ​​determined for each target compound, and peak detection is performed, and the peaks are grouped based on the retention time of the peaks detected in each EIC. Then, the presence or absence of the target compound or the presence of impurities is determined by using the actual mass spectrum obtained at the retention time of the peak top of one peak included in each group and the standard mass spectrum of the target compound. However, the above conventional method is premised on quantifying a target compound whose m / z value is known, and is not suitable for quantifying unknown compounds contained in a sample. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-095253 A Summary of the Invention [Problem to be solved by the invention]

[0006] For the comprehensive analysis of compounds contained in a sample as described above, it is necessary to be able to quantify not only known target compounds contained in the sample, but also unknown compounds, and for this purpose, it is desirable to obtain EICs corresponding to various compounds contained in the sample, whether known or unknown. On the other hand, data collected by chromatography-mass spectrometry also shows ion intensities derived from impurities contained in the mobile phase, for example, and EICs corresponding to such substances that are not the target of analysis are not required.

[0007] In order to obtain an EIC corresponding to a compound that a user wants to analyze, the user generally needs to check the mass spectrum and then specify the m / z value for creating the EIC. However, because the amount of data collected by chromatography mass spectrometry is enormous, such work by the user is very cumbersome, time-consuming, and inefficient. In addition, since such work is highly dependent on the skill and experience of the operator in charge, it is inevitable that the results will vary, and compounds may be left out or errors may occur.

[0008] The present invention has been made to solve these problems, and its main object is to provide a chromatography mass spectrometer and a chromatography mass analysis data processing method that extracts EICs corresponding to target compounds and unknown compounds in a sample as thoroughly as possible from data collected by chromatography mass analysis, without the need for complicated operations by the user. [Means for solving the problem]

[0009] One aspect of the chromatographic mass spectrometer according to the present invention, which has been made to solve the above problems, is a chromatographic mass spectrometer comprising a data processing unit that processes data collected by chromatographic mass analysis, the data processing unit comprising: a first peak detection unit that creates a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performs peak detection on the chromatogram; an extracted ion chromatogram creating unit that creates an extracted ion chromatogram for the mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected by the first peak detection unit; a second peak detection unit that performs peak detection on the extracted ion chromatogram created by the extracted ion chromatogram creation unit and acquires the retention time of the peak top of the detected peak; a grouping unit that classifies the peaks detected by the second peak detection unit into peaks having substantially the same peak top retention time; a selection unit that selects, for each group classified by the grouping unit, one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios; Equipped with.

[0010] In addition, one aspect of a chromatography mass spectrometry data processing method according to the present invention, which has been made to solve the above problems, is a chromatography mass spectrometry data processing method for processing data collected by chromatography mass spectrometry, comprising the steps of: a first peak detection step of creating a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performing peak detection on the chromatogram; an extracted ion chromatogram creating step of creating an extracted ion chromatogram for the mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected in the first peak detection step; a second peak detection step of detecting peaks in the extracted ion chromatogram created in the extracted ion chromatogram creation step and acquiring retention times of the peak tops of the detected peaks; A grouping step of classifying the peaks detected in the second peak detection step into groups of peaks having substantially the same retention time at the peak top; a selection step of selecting one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios for each group classified in the grouping step; has. Effect of the Invention

[0011] According to the above-mentioned aspects of the chromatography mass spectrometer and the chromatography mass analysis data processing method of the present invention, it is possible to extract EICs corresponding to target compounds and unknown impurities and contaminants in a sample from a huge amount of mass spectrum data and chromatogram data collected by chromatography mass analysis without cumbersome work and operations by a user (operator). By performing such processing automatically, it is possible to reduce the burden on the operator. Furthermore, since such processing does not depend on the skill or experience of the operator, it is possible to suppress the variation in the processing results. Furthermore, it is possible to shorten the time required for the work and efficiently analyze the compounds. [Brief description of the drawings]

[0012] [Figure 1] 1 is a configuration diagram of a main part of an LC-MS which is one embodiment of a chromatographic mass spectrometer according to the present invention. [Diagram 2] 1 is a flowchart showing the flow of an automatic EIC extraction process in the LC-MS of this embodiment. [Diagram 3] FIG. 1 shows an example of peaks with close retention times. [Figure 4] FIG. 4 is an explanatory diagram of a process for grouping EICs in which the peaks shown in FIG. 3 are observed. [Diagram 5] FIG. 4 shows the results of grouping EICs in which the peaks shown in FIG. 3 are observed. [Figure 6] FIG. 2 is a conceptual diagram of an automatic EIC extraction process in the LC-MS of the present embodiment. [Figure 7] FIG. 2 shows an example of the display form of an EIC automatically extracted in the LC-MS of this embodiment. [Figure 8] FIG. 13 shows another example of the display form of EICs automatically extracted in the LC-MS of this embodiment. [Figure 9] FIG. 2 is an explanatory diagram of a mass spectrum separation process in the LC-MS of the present embodiment. [Figure 10] FIG. 2 is a diagram showing an example of a mass spectrum in which intensity values ​​have been binarized. [Figure 11]FIG. 2 is a Venn diagram showing an example of the relationship between sets of mass peaks obtained by mass spectrum separation processing in the LC-MS of this embodiment. [Figure 12] FIG. 11 is a Venn diagram showing another example of the relationship between sets of mass peaks obtained by the mass spectrum separation process in the LC-MS of this embodiment. [Figure 13] FIG. 11 is a Venn diagram showing another example of the relationship between sets of mass peaks obtained by the mass spectrum separation process in the LC-MS of this embodiment. [Figure 14] FIG. 11 is a Venn diagram showing another example of the relationship between sets of mass peaks obtained by the mass spectrum separation process in the LC-MS of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an LC-MS according to one embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] Fig. 1 is a configuration diagram of the main parts of an LC-MS according to this embodiment. The LC-MS according to this embodiment includes a liquid chromatograph part (LC part) 1 and a mass spectrometer part (MS part) 2 as measurement parts, a data processor 3, an input part 4, and a display part 5. Note that Fig. 1 omits the illustration of a controller that controls the LC part 1 and the MS part 2 for LC / MS analysis.

[0015] The LC section 1 includes a mobile phase container 10 in which the mobile phase is stored, a liquid delivery pump 11 that draws in the mobile phase and delivers it at a constant flow rate, an injector 12 that injects a sample into the mobile phase at a predetermined timing, and a column 13 that separates various compounds in the sample in the time direction.

[0016] The MS section 2 is a single-type quadrupole mass spectrometer, and includes an ionization section 20 that ionizes compounds contained in the eluate from the column 13, ion guides 21 and 22 that transport the generated ions, a quadrupole mass filter 23 that selectively passes ions having a specific m / z, and a detector 24 that detects the ions. Note that the MS section 2 is not limited to a single-type quadrupole mass spectrometer, and other types of mass spectrometers, such as a triple quadrupole mass spectrometer or a quadrupole-time-of-flight mass spectrometer, may also be used.

[0017] The data processing unit 3, which receives a detection signal from the detector 24 of the MS unit 2, includes, as functional blocks, a data storage unit 30, an EIC extraction processing unit 31, a mass spectrum separation processing unit 32, an EIC display processing unit 33, a mass spectrum display processing unit 34, and a coelution determination unit 35. The EIC extraction processing unit 31 includes, as lower functional blocks, a TIC creation unit 310, a TIC peak detection unit 311, a TIC peak selection unit 312, a tentative EIC creation unit 313, an EIC peak detection unit 314, an EIC grouping unit 315, and an EIC selection unit 316.

[0018] In general, the data processing unit 3 and the control unit (not shown) are implemented as hardware in the form of a personal computer comprising a CPU, memory, etc., or a more powerful computer called a workstation, and at least a part of their functions are realized by executing dedicated processing and control software (computer program) preinstalled on the computer. In this case, the input unit 4 is a pointing device such as a keyboard or a mouse attached to the computer, and the display unit 5 is a display monitor attached to the computer.

[0019] The computer program can be provided to the user by being stored in a computer-readable non-transitory recording medium, such as a CD-ROM, a DVD-ROM, a memory card, or a USB memory (dongle). The program can also be provided to the user in the form of data transfer via a communication line such as the Internet. Furthermore, the program can be pre-installed in a computer that is a part of the system (strictly speaking, a storage device that is a part of the computer) when the user purchases the system.

[0020] First, a brief description will be given of the LC / MS analysis operation performed in the LC-MS of this embodiment by the LC section 1 and the MS section 2. This LC / MS analysis operation is the same as that performed in a general LC-MS.

[0021] In the LC section 1, a liquid delivery pump 11 draws in a mobile phase from a mobile phase container 10 and delivers it to a column 13 at a constant flow rate. An injector 12 injects a sample into the mobile phase at a predetermined timing. The injected sample is carried by the flow of the mobile phase and introduced into the column 13. Various compounds in the sample are separated in the time direction while passing through the column 13 due to interactions with the liquid phase of the column 13, and are eluted from the outlet of the column 13 with a time lag.

[0022] Compounds in the eluate from the column 13 are ionized in the ionization section 20, and the ions generated in the ionization section 20 are transported by the ion guides 21, 22 and introduced into the quadrupole mass filter 23. When simultaneously analyzing compounds including unknown compounds in a sample, the quadrupole mass filter 23 is driven to repeatedly perform scan measurements in a predetermined m / z range. The detector 24 outputs, as a detection signal, an ion intensity according to the amount of ions that have passed through the quadrupole mass filter 23 driven in this manner. Therefore, detection signals corresponding to the mass spectrum in a predetermined m / z range are repeatedly input to the data processing section 3 during a predetermined analysis time period starting from the time when the sample is injected into the mobile phase in the LC section 1.

[0023] The data storage unit 30 in the data processing unit 3 includes an analog-to-digital conversion unit, and digitizes and stores the detection signals sequentially input over time. Therefore, the data storage unit 30 stores a large amount of data constituting the mass spectrum and the chromatogram.

[0024] Next, an example of characteristic data processing performed using data collected by performing LC / MS analysis on a certain sample and stored will be described with reference to Figures 2 to 6. Figure 2 is a flowchart showing the flow of automatic EIC extraction processing performed in the data processing unit 3.

[0025] For example, when the user performs a predetermined operation on the input unit 4, the EIC extraction processing unit 31 starts the automatic EIC extraction process. First, the TIC creating unit 310 creates a total ion chromatogram (TIC) based on the data read out from the data storage unit 30 (step S1).

[0026] This chromatogram does not have to be a chromatogram corresponding to a specific m / z value, but may be a chromatogram reflecting peaks observed at various m / z values. Therefore, instead of a TIC, a base peak chromatogram (BPC) or a multi-ion chromatogram (MIC) may be used. A MIC is a chromatogram obtained by adding up the ion intensities in an m / z range excluding one or more specific m / z values ​​or m / z ranges in the entire measured m / z range.

[0027] In addition, an EIC is not necessarily a chromatogram showing the time change of ion intensity for one m / z value, but may include a chromatogram showing the time change of the sum of ion intensities for multiple m / z values, and therefore may include an MIC. However, in this specification, an EIC refers to a chromatogram showing the time change of ion intensity for one specific m / z value, and is distinguished from an MIC.

[0028] The TIC peak detection unit 311 performs peak detection on one of the TICs created by the TIC creation unit 310 according to a predetermined criterion, and obtains the peak start and end times for each detected peak (step S2). Fig. 6(A) shows an example of a TIC. When peak detection is performed on this TIC, two peaks are detected. The start and end points of the first peak are t1 and t2, and the time range from t1 to t2 is the peak range W of this peak.

[0029] Next, the TIC peak selection unit 312 determines whether the peak shape of each of the TIC peaks detected by the TIC peak detection unit 311 satisfies a predetermined condition set in advance, and excludes the TIC peaks that do not satisfy the predetermined condition (step S3).

[0030] The main purpose of this step is to eliminate noise peaks, for example, originating from the mobile phase, as much as possible, and the predetermined conditions may be determined to meet this purpose. As one example, the predetermined condition may be that the slope of the tangent to the first half (rising) and / or second half (falling) of the peak meets a criterion. As another example, the predetermined condition may be that the coefficient of variation (relative variation) of the intensity values ​​of each point constituting the TIC peak is calculated, and that the coefficient of variation meets a criterion. This coefficient of variation is usually a value calculated by dividing the standard deviation by the average.

[0031] It should be noted that by adding the predetermined condition in step S3 to the conditions for detecting the TIC peak in step S2, steps S2 and S3 can be executed substantially simultaneously.

[0032] Thereafter, the tentative EIC creation unit 313 acquires data constituting a large number of mass spectra acquired at each time point within the peak range (start point to end point) for each TIC peak remaining after the selection in step S3, and performs centroiding for each mass spectrum to calculate a centroid spectrum. When centroiding, a kind of noise removal process may be performed, for example, by excluding mass peaks whose signal intensity is equal to or less than a threshold. Then, the tentative EIC creation unit 313 obtains the m / z values ​​of mass peaks observed in all centroid spectra included in the entire peak range, and creates an EIC for this m / z value (step S4). This EIC may be for the entire measurement range, or may be for only the peak range of the original TIC peak.

[0033] In addition, among multiple centroid spectra obtained at each time point within the peak range, it is inevitable that m / z shifts will occur in mass peaks that theoretically have the same m / z value due to limitations in the mass accuracy of the MS unit 2. For this reason, it is advisable to determine the allowable range of m / z shifts in advance and determine the m / z value by estimating that mass peaks included in the allowable range have the same m / z value. This makes it possible to avoid a situation in which multiple EICs corresponding to the same ion are created due to performance limitations of the MS unit 2.

[0034] For example, the centroid spectrum obtained at a certain time point in the peak range W of the first TIC peak in FIG. 6(A) is shown in FIG. 6(B), and no mass peaks other than the mass peaks in this centroid spectrum are present in the peak range W. In this case, EICs are created for four m / z values, m / z1, m / z2, m / z3, and m / z4, respectively. These EICs are shown in FIG. 6(C). However, in FIG. 6(C), EICs outside the peak range W are also depicted. In this manner, one or more EICs can be created for each TIC peak.

[0035] The EIC peak detection unit 314 performs peak detection for each EIC according to a predetermined criterion and obtains the retention time of the peak top of the detected EIC peak (step S5). At this time, the EIC peak detection unit 314 excludes EICs in which no peak is detected (step S6).

[0036] In Fig. 6(C), the EIC of m / z 1 corresponds to a compound contained in the mobile phase (e.g., an impurity mixed in the mobile phase). Although such compounds that appear throughout the measurement time show mass peaks in the centroid spectrum as shown in Fig. 6(B), the change in intensity in the time direction is small, so that no clear peak appears in the EIC. Therefore, such EICs are excluded in the processing of step S6.

[0037] Next, the EIC grouping unit 315 groups the EIC peaks detected by the EIC peak detection unit 314 into groups of peaks having substantially the same peak top retention time (i.e., within a time range that can be considered to be the same) (step S7). The time range that can be considered to be in the same group may be constant regardless of the retention time, but may be set to be wider as the retention time of the peak increases.

[0038] Here, an example of the rules for grouping EIC peaks will be described with reference to FIGS. In this example, when multiple EIC peaks that exist in the same peak range are grouped, the peak top intensity is prioritized, and groups are formed in descending order of intensity, and EIC peaks that have already been grouped are not assigned to other groups.

[0039] Now, assume that three EIC peaks A, B, and C with the retention times and intensities shown in Figure 3 exist in the peak range of one TIC peak. Also assume that the time range in which the retention times of the peak tops can be considered to be the same is within 1 second. Figure 4 is a schematic diagram of the chromatogram waveforms in the vicinity of the three EIC peaks A, B, and C shown in Figure 3.

[0040] As described above, since grouping is performed with priority given to the intensity of the peak top, the EIC grouping unit 315 selects the EIC peak C with the highest intensity and sets it as a reference. The retention time (61 seconds) of the EIC peak C and the peak top retention time (60 seconds) of the EIC peak B with the next highest intensity are within 1 second. Therefore, the EIC grouping unit 315 classifies the EIC peaks C and B into the same group. Next, when the retention time (61 seconds) of the EIC peak A with the next highest intensity after the EIC peak B is checked, the difference exceeds 1 second from the retention time (61 seconds) of the EIC peak C. Therefore, the EIC grouping unit 315 classifies the EIC peak A into a different group from the EIC peaks C and B. Therefore, in this example, as a result of grouping the EIC peaks, two groups #1 and #2 are formed as shown in FIG. 5.

[0041] When peak detection is performed for the three EICs shown in Fig. 6(C) (excluding the EIC of m / z1 as described above) and the detected peaks are grouped, the peaks of m / z2 and m / z3 are classified into the same group, and the peak of m / z4 is classified into another group, as shown in Fig. 6(D). That is, in this example, it can be determined that two groups exist within the time range t1 to t2 of the peak range W of one TIC peak.

[0042] Ions that show m / z values ​​belonging to the same group can be presumed to be different ions derived from the same compound. For example, they are isotopic ions with the same chemical structure but different isotopes of the constituent elements, or adduct ions in which an ion of a certain compound is added to another molecule (adduct) during ionization. They may also be multivalent ions with different valences derived from the same compound, or polymeric ions that are polymerized during ionization. These ions should be classified into the same group because they basically have the same retention time and only differ in m / z value. On the other hand, the EIC peak of m / z 4 in FIG. 6(D) exists within the peak range W of one TIC peak, but the retention time of the EIC peak is clearly different from the retention times of the EIC peaks of m / z 2 and m / z 3, so it can be presumed that they are not ions derived from the same compound. In this way, multiple peaks that overlap in the TIC peak can be separated into chromatographic peaks corresponding to each compound.

[0043] After grouping of EIC peaks as described above for each TIC peak is completed, the EIC selection unit 316 selects one m / z value for each group. Multiple m / z values ​​may be selected instead of one, but one is usually sufficient. Typically, the m / z value with the maximum peak top intensity is selected, but the selection method is not limited to this. The EIC selection unit 316 lists the m / z values ​​selected for each group (step S8). This completes the automatic extraction of EICs from the original TIC (actually, the extraction of m / z values ​​corresponding to EICs).

[0044] Based on the grouping result, the coelution determination unit 35 determines whether or not multiple groups exist in the peak range of one TIC peak. If multiple groups exist, it is determined that the multiple groups coelute with each other (step S9). In the example of FIG. 6(D), it can be determined that the group including the compounds with m / z values ​​of m / z2 and m / z3 and the group including the compound with m / z value of m / z4 coelute with each other.

[0045] The EIC display processing unit 33 draws EICs corresponding to each m / z value listed in the EIC selection unit 316 and displays them on the display unit 5 (step S10). Usually, many EICs are obtained, and they may be overlaid with different display colors, or may be stacked vertically. Alternatively, many EICs may be displayed in a switchable manner using tabs or the like. In addition, as shown in FIG. 6(C), ETCs over a wide time range (maximum the entire measurement time range) including each EIC peak may be displayed, or for each ETC, the peak portion of the EIC peak, that is, only the range from the start point to the end point of the peak, or a waveform of a predetermined narrow time range including the peak may be cut out and displayed.

[0046] Figure 7 shows an example in which only the waveforms in the time range around the peak portions of the two EIC peaks extracted in the example of Figure 6 are cut out and displayed in an overlapping manner. Figure 8 shows an example in which only the peak portions of those two EIC peaks are cut out and displayed side-by-side vertically. By displaying only the EIC peak portions in this way, the user can easily grasp the waveforms of the chromatographic peaks corresponding to the compounds.

[0047] When displaying the EICs in this way, the judgment results regarding coelution may also be displayed. For example, a curve showing the waveform of the time range where each EIC peak coelutes may be displayed in a color different from that of the other time ranges, or the background of the time range where coelution occurs may be displayed in a color different from that of the other time ranges. It is preferable that such an EIC display mode be switchable according to a user setting.

[0048] Furthermore, in the LC-MS of this embodiment, by utilizing the separation results of the ETC peaks, mass spectral information such as a mass spectrum mainly reflecting each compound or a mass spectrum excluding mass peaks derived from a specific compound can be obtained from a mass spectrum containing a mixture of mass peaks derived from multiple compounds.

[0049] As an example, consider the case where two chromatographic peaks X and Y originating from different compounds with close retention times overlap as shown in FIG. 9(B) and appear as a single chromatographic peak U in the TIC as shown in FIG. 9(A). Since a part of the chromatographic peak Y overlaps with the peak top time tx of the chromatographic peak X, the mass spectrum acquired at time tx contains a mixture of mass peaks originating from two compounds corresponding to the two chromatographic peaks X and Y. On the other hand, since a part of the chromatographic peak X overlaps with the peak top time ty of the chromatographic peak Y, the mass spectrum acquired at time ty also contains a mixture of mass peaks originating from two compounds corresponding to the two chromatographic peaks X and Y. In addition, as described in the example of FIG. 6, the chromatographic peak U on the TIC may contain not only chromatographic peaks originating from compounds corresponding to the chromatographic peaks X and Y, but also chromatographic peaks originating from impurities contained in the mobile phase. Therefore, the mass spectrum separation processor 32 calculates mass spectrum information corresponding to the chromatographic peak X from mass spectrum data in which mass peaks derived from a plurality of compounds are mixed, by any of the following methods.

[0050] <Method 1> As a result of the EIC extraction process described above, the time tx of the peak top of chromatographic peak X is determined. Then, the mass spectrum separation processor 32 collects all mass peaks observed in the mass spectrum (centroid spectrum) acquired at time tx, and regards this as mass spectrum information corresponding to chromatographic peak X. However, the mass peak referred to here adopts, for example, one of the following two definitions A and B.

[0051] (Definition A) The intensity of the mass peaks is essentially ignored, and only the m / z value at which the centroid peak exists is regarded as peak information. In other words, simply put, the intensity of each mass peak is binarized as "0" or "1", and only mass peaks with an intensity of "1" are collected. Therefore, a certain mass spectrum can be represented as a set of m / z values ​​{Ma, Mb, Mc, ...} at which mass peaks exist. Furthermore, the mass spectrum is represented as a bar-displayed mass spectrum in which the intensity at each m / z on the m / z axis is a binary value, as shown in Figure 10.

[0052] (Definition B) Peak information is a pair of m / z value and intensity of a mass peak observed in a mass spectrum at the time tx of the peak top of chromatographic peak X, or a pair of m / z value and intensity of a mass peak observed in an average mass spectrum of multiple mass spectra obtained in a predetermined time range (near the peak top) centered on the time tx of the peak top of chromatographic peak X. Therefore, a certain mass spectrum can be represented as a set of pairs of m / z value and intensity {(Ma, Ia), (Mb, Ib), (Mc, Ic), ...} where mass peaks exist.

[0053] When definition A is adopted in method 1, the mass spectrum as shown in Fig. 10 (mass spectrum ignoring intensity information in the original mass spectrum) obtained at the peak top time tx of chromatographic peak X is the mass spectrum corresponding to chromatographic peak X. On the other hand, when definition B is adopted in method 1, the set of mass peaks given by definition B is the mass spectrum corresponding to chromatographic peak X as it is.

[0054] The relationship between the mass peaks observed in the mass spectra at the peak top times of the chromatographic peaks X, Y, and U is shown in a Venn diagram in FIG. 11. [U], [X], and [Y] respectively indicate sets of mass peaks observed in the mass spectra obtained at the peak top times of the chromatographic peaks U, X, and Y. The shaded portion in FIG. 11, i.e., [X], is the mass spectrum information obtained by method 1, which is a set of mass peaks observed in the mass spectrum at the peak top of the chromatographic peak X. As shown in the figure, the mass spectrum information obtained by method 1 includes some of the mass peaks derived from the compound corresponding to the chromatographic peak Y, but does not include mass peaks derived from the compound corresponding only to the chromatographic peak U.

[0055] <Method 2> The mass spectrum separation processing unit 32 subtracts the mass peaks observed in the mass spectrum at the time ty of the peak top of chromatographic peak Y from the set of mass peaks [X] obtained by the above-mentioned method 1, and regards the remaining mass peaks as mass spectrum information corresponding to chromatographic peak X.

[0056] When Definition A is adopted in Method 2, the intensity of each mass peak is not taken into consideration. Therefore, the mass spectrum formed in this case is a mass spectrum corresponding to the difference set between the set of mass peaks derived from chromatographic peak X and the set of mass peaks derived from chromatographic peak Y. In other words, it is mass spectrum information corresponding to the shaded portion in the Venn diagram shown in FIG.

[0057] On the other hand, when definition B is adopted in method 2, the subtraction of mass peaks is defined as the subtraction of intensity values ​​between mass peaks having the same m / z value. However, this subtraction can be performed based on the distributed intensity value by distributing the intensity of the mass peak of the corresponding m / z value on the mass spectrum at time tx according to the intensity ratio between chromatographic peak X and chromatographic peak Y at the time tx. Therefore, in this case, unlike the case where definition A is adopted, mass peaks showing intensity values ​​estimated to be derived from the compound corresponding to chromatographic peak X remain in the range indicated by [X] ∩ [Y] in the Venn diagram shown in FIG. 12.

[0058] <Method 3> The mass spectrum separation processing unit 32 collects the mass peaks observed in the mass spectrum at the peak top time tx of chromatographic peak X and the mass peaks observed in the mass spectrum at the peak top time tu of chromatographic peak U, subtracts the mass peak observed in the mass spectrum at the peak top time ty of chromatographic peak Y, and regards the remaining mass peaks as mass spectrum information corresponding to chromatographic peak X.

[0059] When Definition A is adopted in Method 3, the mass spectrum information formed thereby corresponds to the shaded portion in the Venn diagram shown in Figure 13, that is, the complement of the set of mass peaks [Y] observed in the mass spectrum at the peak top time ty of chromatographic peak Y. On the other hand, when Definition B is adopted in Method 3, the addition and subtraction of mass peaks can be defined as the addition and subtraction of intensity values ​​of mass peaks with the same m / z value, as in Method 2.

[0060] <Method 4> The mass spectrum separation processing unit 32 adds a set of mass peaks [X]∩[Y] observed in both the mass spectrum of chromatographic peak X at the peak top time tx and the mass spectrum of chromatographic peak Y at the peak top time ty to the complement of the set of mass peaks [Y] obtained by method 3, and regards this as mass spectrum information corresponding to chromatographic peak X.

[0061] When definition A is adopted in method 4, the mass spectrum information thus formed corresponds to the shaded portion in the Venn diagram shown in FIG. 14, that is, the complement of the set of mass peaks observed only in the mass spectrum of chromatographic peak Y at time ty. On the other hand, when definition B is adopted in method 4, like methods 2 and 3, the addition and subtraction of mass peaks can be defined as the addition and subtraction of intensity values ​​between mass peaks with the same m / z value.

[0062] Using any of the above-mentioned methods 1 to 4, a mass spectrum derived from a compound corresponding to chromatographic peak X or mass peak information in the mass spectrum can be obtained. Similarly, a mass spectrum derived from a compound corresponding to chromatographic peak Y overlapping with chromatographic peak X or mass peak information in the mass spectrum can be obtained. The mass spectrum display processing unit 34 displays the mass spectrum calculated by the mass spectrum separation processing unit 32 on the screen of the display unit 5. It is preferable that the user is allowed to appropriately select which of the above methods 1 to 4 to use and which of definitions A and B to use. In addition, the method for calculating the mass spectrum corresponding to each chromatographic peak is not limited to the above-described methods and can be changed as appropriate.

[0063] As described above, according to the LC-MS of this embodiment, EICs corresponding to significant compounds contained in a sample can be automatically and comprehensively extracted and presented to the user. In addition, it is possible to automatically determine whether or not there are compounds that are eluted in a time-overlapping manner, and which compounds are overlapping, and to notify the user of this. Furthermore, it is possible to present to the user mass spectra corresponding to each of a plurality of compounds that are eluted in a time-overlapping manner.

[0064] Although the above embodiment is an application of the present invention to an LC-MS, it is clear that the present invention can also be applied to a GC-MS.

[0065] Furthermore, the above embodiment is merely one example of the present invention, and it is natural that any appropriate modifications, amendments, additions, etc. made within the spirit of the present invention will be encompassed within the scope of the claims of the present application.

[0066] [Various aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0067] (Item 1) One aspect of the chromatographic mass spectrometer according to the present invention is a chromatographic mass spectrometer comprising a data processing unit that processes data collected by chromatographic mass spectrometry, the data processing unit comprising: a first peak detection unit that creates a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performs peak detection on the chromatogram; an extracted ion chromatogram creating unit that creates an extracted ion chromatogram for a mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected by the first peak detection unit; a second peak detection unit that performs peak detection on the extracted ion chromatogram created by the extracted ion chromatogram creation unit and acquires the retention time of the peak top of the detected peak; a grouping unit that classifies the peaks detected by the second peak detection unit into peaks having substantially the same peak top retention time; a selection unit that selects, for each group classified by the grouping unit, one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios; Equipped with.

[0068] (Item 8) One aspect of the chromatography-mass spectrometry data processing method according to the present invention is a chromatography-mass spectrometry data processing method for processing data collected by chromatography-mass spectrometry, comprising the steps of: a first peak detection step of creating a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performing peak detection on the chromatogram; an extracted ion chromatogram creating step of creating an extracted ion chromatogram for the mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected in the first peak detection step; a second peak detection step of detecting peaks in the extracted ion chromatogram created in the extracted ion chromatogram creation step and acquiring retention times of the peak tops of the detected peaks; A grouping step of classifying the peaks detected in the second peak detection step into groups of peaks having substantially the same retention time at the peak top; a selection step of selecting one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios for each group classified in the grouping step; has.

[0069] The chromatographic mass spectrometer described in paragraph 1 is typically an LC-MS or a GC-MS. In this case, the MS section can be of various types, such as a single quadrupole mass spectrometer, a triple quadrupole mass spectrometer, a quadrupole-time-of-flight mass spectrometer, or an ion trap mass spectrometer.

[0070] (Item 2) In the chromatography mass spectrometer described in item 1, the chromatogram reflecting the signal intensities at the plurality of mass-to-charge ratios may be any one of TIC, BPC, or MIC.

[0071] According to the chromatographic mass spectrometer described in paragraphs 1 and 2 and the chromatographic mass analysis data processing method described in paragraph 8, EICs corresponding to target compounds and unknown impurities and contaminants in a sample can be extracted without omission from a huge amount of mass spectrum data and chromatogram data collected by chromatographic mass analysis, without any cumbersome work or operation by a user (operator). By performing such processing automatically, the burden on the operator can be reduced. In addition, since such processing does not depend on the skill or experience of the operator, the variation in the processing results can be suppressed. In addition, the time required for the work can be shortened, and the analysis of compounds can be performed efficiently.

[0072] (Item 3) The chromatographic mass spectrometer according to item 1 or 2 may further include a co-elution determination unit that determines co-elution based on whether or not there are multiple groups that share the same time range.

[0073] According to the chromatographic mass spectrometer described in item 3, the presence or absence of co-elution and the presence or absence of co-eluted compounds can be easily and accurately determined.

[0074] (Item 4) The chromatographic mass spectrometer according to any one of items 1 to 3 may further include a peak selection unit that removes peaks detected by the first peak detection unit whose peak shapes do not satisfy a predetermined standard, and the peaks remaining after removal by the peak selection unit may be subjected to processing by the extracted ion chromatogram creation unit.

[0075] In the chromatographic mass spectrometer described in item 4, the peak selection section removes noise peaks originating from the mobile phase, etc. This makes it possible to more accurately extract EICs corresponding to compounds present in a sample.

[0076] (Item 5) In the chromatographic mass spectrometer described in any one of items 1 to 4, the selection unit selects one or more extracted ion chromatograms corresponding to representative mass-to-charge ratios for each group, and the chromatographic mass spectrometer may further include a display processing unit that displays the extracted ion chromatograms for each group selected by the selection unit on a display unit.

[0077] The display processing unit may display a plurality of EICs on the display unit simultaneously, for example, overlapping or arranging them, or may display them in a switchable manner in response to an instruction.

[0078] According to the chromatographic mass spectrometer described in item 5, it is possible to present to the user EICs corresponding to significant compounds contained in a sample.

[0079] (Item 6) In the chromatographic mass spectrometer described in Item 5, the display processing unit may be configured to cut out and display a waveform of a peak range from the start point to the end point of a peak appearing in an extracted ion chromatogram, or a waveform of a predetermined time range including the peak range.

[0080] According to the chromatographic mass spectrometer described in item 6, it is possible to present to the user only useful peak waveforms around the retention times at which significant compounds contained in a sample appear.

[0081] (Item 7) In the chromatographic mass spectrometer described in any one of Items 1 to 6, the data processing unit may further include a mass spectrum separation processing unit that uses information of a peak observed in an extracted ion chromatogram selected by the selection unit to extract information of a mass peak corresponding to the peak from the collected data and creates a mass spectrum.

[0082] According to the chromatographic mass spectrometer described in item 7, not only can an EIC be obtained for each compound contained in a sample, but also a mass spectrum for each compound can be obtained. This makes it possible to, for example, confirm the type of compound, estimate its structure, etc., by using the mass spectrum. [Explanation of symbols]

[0083] 1...LC section 10…Mobile phase container 11...Liquid delivery pump 12...Injector 13…Column 2...MS section 20...Ionization section 21, 22…Ion guide 23...Quadrupole mass filter 24…Detector 3. Data processing section 30...Data storage section 31...EIC extraction processing section 310…TIC creation department 311…TIC peak detector 312…TIC peak selection section 313…Temporary EIC Creation Department 314…EIC peak detector 315…EIC Grouping Department 316...EIC selection department 32...Mass spectrum separation processing unit 33...EIC display processing unit 34...Mass spectrum display processing unit 35…Co-elution determination section 4. Input section 5...Display section

Claims

1. A chromatographic mass spectrometer comprising a data processing unit for processing data collected by chromatographic mass spectrometry, the data processing unit comprising: a first peak detection unit that creates a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performs peak detection on the chromatogram; an extracted ion chromatogram creating unit that creates an extracted ion chromatogram for a mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected by the first peak detection unit; a second peak detection unit that performs peak detection on the extracted ion chromatogram created by the extracted ion chromatogram creation unit and acquires a retention time of a peak top of the detected peak; a grouping unit that classifies the peaks detected by the second peak detection unit into peaks having substantially the same peak top retention time; a selection unit that selects, for each group classified by the grouping unit, one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios; A chromatography mass spectrometer comprising:

2. 2. The chromatography mass spectrometer according to claim 1, wherein the chromatogram reflecting the signal intensities at the plurality of mass-to-charge ratios is any one of a total ion chromatogram, a base peak chromatogram, and a multi-ion chromatogram.

3. The chromatography mass spectrometer according to claim 1 , further comprising a co-elution determination unit that determines co-elution based on whether or not there are multiple groups that share the same time range.

4. 2. The chromatographic mass spectrometer according to claim 1, further comprising a peak selection unit that removes peaks detected by the first peak detection unit whose peak shapes do not satisfy a predetermined standard, and provides peaks remaining after removal by the peak selection unit for processing by the extracted ion chromatogram creation unit.

5. 2. The chromatography mass spectrometer according to claim 1, wherein the selection unit selects one or more extracted ion chromatograms corresponding to representative mass-to-charge ratios for each group, and the chromatography mass spectrometer further comprises a display processing unit that displays the extracted ion chromatograms for each group selected by the selection unit on a display unit.

6. 6. The chromatography mass spectrometer according to claim 5, wherein the display processing unit cuts out and displays a waveform in a peak range from a start point to an end point of a peak appearing in the extracted ion chromatogram or in a predetermined time range including the peak range.

7. 2. The chromatography mass spectrometer according to claim 1, wherein the data processing unit further comprises a mass spectrum separation processing unit that uses information of a peak observed in an extracted ion chromatogram selected by the selection unit to extract information of a mass peak corresponding to the peak from the collected data and creates a mass spectrum.

8. 1. A method for processing data collected by chromatography-mass spectrometry, comprising: a first peak detection step of creating a chromatogram reflecting signal intensities at a plurality of mass-to-charge ratios based on the collected data and performing peak detection on the chromatogram; an extracted ion chromatogram creating step of creating an extracted ion chromatogram for the mass-to-charge ratio of a centroid peak observed in a mass spectrum obtained in a time range of at least a portion of the peak detected in the first peak detection step; a second peak detection step of detecting peaks in the extracted ion chromatogram created in the extracted ion chromatogram creation step and acquiring retention times of the tops of the detected peaks; a grouping step of classifying the peaks detected in the second peak detection step into groups of peaks having substantially the same retention time at the peak top; a selection step of selecting one or more representative mass-to-charge ratios or extracted ion chromatograms corresponding to the mass-to-charge ratios for each group classified in the grouping step; A chromatography mass spectrometry data processing method comprising the steps of:

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