Chromatography Mass Spectrometer

Abstract

A chromatograph mass spectrometry device according to one aspect of the present invention comprises: a measuring unit (1) including a chromatograph unit and a mass spectrometry unit; an ion extracting unit (21) for acquiring a mass spectrum of a compound of interest from a spectrum library (5) in which a standard mass spectrum and compound information including a holding time or a holding indicator are recorded, and for using an intensity of a mass peak observed in the mass spectrum and an m / z value corresponding to the mass peak to extract a monitor ion for each compound of interest; a database creating unit (22) for registering the compound information of the compound of interest and the m / z value of the monitor ion in a database (23); a compound specification accepting unit (24) for accepting a specification, from a user, relating to a target compound to be analyzed, among the compounds registered in the database; a method creating unit (24) for using the registration information in the database to create an analysis method for the target compound; a control unit (26) for controlling an operation of the measuring unit so as to carry out an analysis of a specimen of interest, in accordance with the analysis method; and a compound identifying unit (28) for using an analysis result for the specimen of interest, and the analysis method or the registration information in the database, to identify a compound in the specimen of interest.

Description

[Technical field]

[0001] The present invention relates to a chromatograph mass spectrometer that combines a chromatograph, such as a gas chromatograph, a liquid chromatograph, or a supercritical fluid chromatograph, with a mass spectrometer. [Background technology]

[0002] In recent years, chromatograph mass spectrometers such as gas chromatograph mass spectrometers (GC-MS) and liquid chromatograph mass spectrometers (LC-MS) have been widely used in various fields such as testing for residual pesticides in food, testing for pollutants in environmental water, and metabolomics analysis of biological samples. The following explanation will mainly use GC-MS as an example, but it will be clear from the explanation below that the situation is the same for LC-MS and supercritical fluid chromatograph mass spectrometers (SFC-MS), etc.

[0003] When identifying an unknown compound in a sample using GC-MS, the pattern of the measured mass spectrum at the retention time near the peak top of a chromatographic peak detected in a total ion chromatogram (TIC) is generally compared with that of a standard mass spectrum recorded in a spectrum library, and the compound is identified by determining whether the similarity is equal to or higher than a predetermined threshold or shows a high value (see Patent Document 1, etc.). This method is called non-target analysis because the compound to be analyzed is not specified in advance. Well-known spectral libraries for GC / MS include the spectral library published by the National Institute of Standards and Technology (NIST) in the United States and the Wiley Registry provided by Wiley, Inc. in the United States.

[0004] In non-target analysis, when a small peak is buried in adjacent peaks in the TIC, it is difficult to identify the compound corresponding to this small peak. In some cases, analytical processing such as deconvolution is used to separate such overlapping peaks. However, since deconvolution extracts a large number of peaks, including peaks derived from noise, it requires a lot of effort to find peaks derived from compounds actually contained in the sample. In addition, when a sample contains a large number of compounds, it is difficult to extract peaks with sufficient accuracy even if deconvolution is applied.

[0005] On the other hand, when the compound to be confirmed as being present in the sample, i.e. the target compound, is already determined, GC / MS analysis is performed using a pre-created analysis method based on the mass-to-charge ratio (m / z: strictly speaking, it is "m / z" in italics, but in this specification it is called "m / z" or "mass-to-charge ratio") value and retention time (index) of the monitor ion (often called "quantitative ion" in the case of quantitative analysis), which is a representative ion derived from that compound, and the compound is identified from the analysis results. This method is called target analysis.

[0006] In target analysis, peaks can be detected from an extracted ion chromatogram (also commonly referred to as a "mass chromatogram") at the m / z value of the monitor ion. Therefore, even if a small peak is buried in adjacent peaks on the TIC, the peak can be detected accurately and efficiently to identify the compound (see Non-Patent Document 1, etc.). In particular, a multi-component simultaneous analysis method that utilizes the high identification accuracy and efficiency of such target analysis to search for many types of compounds (500 to 1000 or more compounds) as target compounds is known as wide target analysis. In recent years, wide target analysis has attracted attention as a very effective method in metabolomics analysis and the like. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2018 / 138901 [Non-patent literature]

[0008] [Non-Patent Document 1] "GC / MS Forensic Toxicology Database Ver.2", [Online], [Searched November 30, 2021], Shimadzu Corporation, Internet<URL: https: / / www.an.shimadzu.co.jp / gcms / dpd.htm> Summary of the Invention [Problem to be solved by the invention]

[0009] To perform a target analysis using GC-MS, it is necessary to create an analytical method for the target analysis prior to the analysis. To do this, the user must determine the m / z values ​​of the monitor ions and reference ions (also called confirmation ions) for each compound using mass spectra obtained by analyzing standard samples containing the target compounds and mass spectra obtained from a library containing compound information for the target compounds. However, when the number of target compounds is enormous, such as in wide target analysis, this task is quite tedious and requires a great deal of effort and cost. In addition, in general, the ions corresponding to the peaks showing the maximum signal intensity in the mass spectrum are often selected as monitor ions, but in such a method, when the m / z values ​​of the monitor ions and reference ions are small, they often overlap with ions of adjacent compounds. As a result, the compounds may not be identified accurately.

[0010] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a chromatographic mass spectrometer that can identify a large number of compounds with high accuracy while reducing the burden of complicated work on the user in target analysis of a large number of compounds. [Means for solving the problem]

[0011] One aspect of the chromatographic mass spectrometer according to the present invention is A measurement unit including a chromatograph unit that separates compounds in a sample in the time direction and a mass spectrometer unit that detects each of the separated compounds; an ion extraction unit that acquires a mass spectrum of a target compound from a spectrum library that stores compound information including standard mass spectra and retention times or retention indices, and extracts monitor ions for each target compound using the intensities of mass peaks observed in the mass spectrum and mass-to-charge ratio values ​​corresponding to the mass peaks; a database creation unit that registers, in a database, compound information of the target compound and the mass-to-charge ratio value of the monitor ion extracted by the ion extraction unit; a compound specification receiving unit that receives specification by a user of a target compound to be analyzed from among the compounds registered in the database; a method creation unit that creates an analytical method for the target compound by using registered information in the database; A control unit that controls the operation of the measurement unit to perform chromatographic mass spectrometry on a target sample according to the analysis method; a compound identification unit that identifies a compound in the target sample by using a chromatographic mass spectrometry result for the target sample and the analysis method or registered information in the database; Equipped with. Effect of the Invention

[0012] In the above-mentioned aspect of the present invention, the mass-to-charge ratio of a monitor ion suitable for identifying a target compound is automatically extracted and registered in an analysis database, without the user having to carry out the tasks of analyzing a standard sample containing the target compound or extracting an appropriate monitor ion from a mass spectrum obtained for the target compound. As a result, the chromatographic mass spectrometer of the above-mentioned aspect of the present invention can identify a large number of compounds with high accuracy while reducing the burden of complicated tasks on the user in target analysis of a large number of compounds. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a GC-MS system according to one embodiment of the present invention. [Diagram 2] 4 is a flowchart showing an example of a flow of compound identification in the GC-MS system of the present embodiment. [Diagram 3] 3 is a flowchart showing an example of an extraction process of monitor ions and the like in FIG. 2. [Figure 4] FIG. 2 is an explanatory diagram of a registration procedure for a database for target analysis in the GC-MS system of this embodiment. [Diagram 5] FIG. 2 is an explanatory diagram of the registered contents of a method file in the GC-MS system of the present embodiment. [Figure 6] FIG. 2 is a diagram showing an example of the relationship between a mass spectrum and a monitor ion and a reference ion. [Figure 7] FIG. 4 is a diagram showing an example of a monitor ion extraction condition setting screen in the GC-MS system of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] [Configuration of a GC-MS system according to one embodiment] A GC-MS system according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram of the GC-MS system of this embodiment.

[0015] This GC-MS system comprises a measurement section 1 including a GC section 1 A and an MS section 1 B, a control and processing section 2 , an input section 3 , a display section 4 , and a spectral library 5 .

[0016] The GC section 1A includes a sample vaporization chamber 10 that vaporizes a minute amount of liquid sample, a microsyringe 11 that injects the liquid sample into the sample vaporization chamber 10, a column 13 that separates a plurality of compounds in the sample in the time direction, and a column oven 12 that controls the temperature of the column 13. The portion for introducing the sample into the column 13 can be changed to one that uses an appropriate method such as the headspace method.

[0017] The MS unit 1B includes, inside a chamber 14 evacuated by a vacuum pump (not shown), an ion source 15 for ionizing a target compound by an ionization method such as electron ionization (EI), an ion lens 16 for focusing the generated ions, a quadrupole mass filter 17 for separating ions according to their mass-to-charge ratio, a detection unit 18 for outputting a detection signal according to the amount of ions that have reached the chamber, and an analog-to-digital converter (ADC) 19 for converting the detection signal into digital data. Here, a quadrupole mass filter is used as the mass separator, but other types of mass separators such as a time-of-flight mass separator or an ion trap may also be used.

[0018] The control / processing unit 2 mainly has a function of controlling the operation of the measurement unit 1 and a function of processing data obtained by the measurement unit 1. The control / processing unit 2 includes, as functional blocks, a library reading unit 20, an ion extraction unit 21, a database creation unit 22, a target analysis database 23, an analysis method creation unit 24, an analysis method storage unit 25, an analysis control unit 26, a data storage unit 27, and a compound identification unit 28.

[0019] The actual entity of the control / processing unit 2 is a computer such as a personal computer, and the functions of each functional block can be realized by executing control / processing software preinstalled on the computer. In this case, the input unit 3 is a keyboard and a pointing device (mouse, etc.) attached to the computer, and the display unit 4 is a display monitor attached to the computer.

[0020] The spectral library 5 is a kind of database that contains compound information for many compounds. This compound information includes the compound name, CAS registration number, molecular weight, molecular formula, structural formula, retention index (or retention time), and mass spectrum. This spectral library 5 can use a widely available spectral library such as those provided by NIST or Wiley, but it can also be one created or provided by an instrument manufacturer for a specific use or purpose, or one created by the user.

[0021] 1, the spectral library 5 is provided separately from the control / processing unit 2, but the control / processing unit 2 may include the spectral library 5. Also, the spectral library 5 may be stored, for example, in an external server separate from this system, that is, not included in this system, and this system may access the server under legitimate authority and download only necessary information from the server.

[0022] [Compound Identification in the GC-MS System of the Present Embodiment] The procedure and processing for identifying compounds by target analysis in the GC-MS system of this embodiment will be described in detail below. FIG. 2 is a flow chart showing an example of a flow of compound identification. FIG. 3 is a flow chart showing an example of an extraction process of monitor ions and the like in FIG. 2. FIG. 4 is an explanatory diagram of a registration procedure of a database for target analysis. FIG. 5 is an explanatory diagram of registered contents of a method file. FIG. 6 is a diagram showing an example of a relationship between a mass spectrum and monitor ions and reference ions.

[0023] In target analysis, it is necessary to prepare a database for target analysis in which compound information on analyzable compounds is registered in advance. This database for target analysis is created as follows.

[0024] First, the user specifies the spectral library 5 to be used for creating the database through the input unit 3 (step S1). However, if only one spectral library 5 is prepared, step S1 can be omitted.

[0025] The user is thing The spectral library 5 from which information is collected is determined, and an instruction to read compound information from the library 5 is given by the input unit 3. In response to this instruction, the library reading unit 20 reads compound information such as compound name, mass spectrum, and retention time (or retention index) from the spectral library 5 (step S2). Generally, the spectral library 5 contains compound information on a large number of compounds, but it is possible to obtain compound information on all of the compounds at once, or to obtain compound information only on specific compounds selected by the user, or further, to obtain compound information only on compounds selected according to conditions specified by the user.

[0026] The database creation unit 22 registers the read compound information in the target analysis database 23 (step S3). FIG. 4(A) is an example of the target analysis database 23 in which compound information has not yet been registered. In this example, the registration items are compound name, retention index, retention time, m / z value of monitor ion, m / z value of reference ion, and mass spectrum. Further registration items such as molecular formula may be added. When the registration process of step S3 is executed, the read compound information is input into each of the registration items of compound name, retention index, retention time, and mass spectrum, as shown in FIG. 4(B). The retention time can be calculated from the retention index. At this point, the m / z values ​​of the monitor ion and reference ion are unknown.

[0027] Next, the ion extraction unit 21 executes a process of extracting monitor ions and reference ions from the mass spectrum registered for each compound as described above (step S4). This extraction process will be described in detail later. Usually, there is one monitor ion and one or more reference ions. The database creation unit 22 registers the m / z values ​​of the monitor ions and reference ions extracted for each compound in the target analysis database 23 (step S5). When the process of step S5 is executed, the m / z values ​​of the extracted monitor ions and reference ions are registered in the target analysis database 23 as shown in FIG. 4(C), and the target analysis database 23 is completed.

[0028] Next, when the user performs a predetermined operation on the input unit 3, the analysis method creation unit 24 displays the target analysis database 23 in table format on the screen of the display unit 4, for example, as shown in Fig. 4(C). The user can confirm the compound names and other information and select the target compound to be identified (step S6). Fig. 5(A) shows the state in which two compounds have been selected as target compounds.

[0029] Then, when the user instructs the creation of an analytical method, the analytical method creation unit 24 obtains registered information such as the retention index of the compound selected as the target compound, and the m / z values ​​of the monitor ion and reference ion from the target analysis database 23, and creates a method file of the analytical method including the measurement conditions for GC / MS analysis and the analysis conditions for each target compound based on the registered information (step S7).

[0030] The measurement conditions include, for example, the carrier gas flow rate in the GC section 1A, the temperature program of the column oven 12, the amount of sample injected, and the m / z range of the scan measurement in the MS section 1B. The analysis conditions are basically the same as the information registered in the target analysis database 23, as shown in FIG. 5(B), and include the retention time, the m / z values ​​of the monitor ions and the reference ions, and the mass spectrum. The m / z range of the scan measurement can be determined so as to cover the m / z values ​​of the monitor ions and the reference ions of all the target compounds. The created method file is stored in the analysis method storage section 25.

[0031] After the method file is created, when the user issues an instruction to execute an analysis, the analysis control unit 26 controls the operation of the measurement unit 1 according to the measurement conditions included in the created method file. As a result, GC / MS analysis of the target sample is executed in the measurement unit 1 (step S8). That is, in the GC unit 1A, the microsyringe 11 drops a predetermined amount of the target sample into the sample vaporization chamber 10 at a predetermined timing. The dropped target sample is vaporized in the sample vaporization chamber 10 and carried by the carrier gas flow to the column 13. The various compounds contained in the target sample are separated in time while passing through the column 13, and are introduced into the ion source 15 of the MS unit 1B.

[0032] Compounds introduced into the ion source 15 are ionized, and the ions generated are introduced into the quadrupole mass filter 17 via the ion lens 16. Under the control of the analysis control unit 26, the quadrupole mass filter 17 operates to repeat a scan measurement over a predetermined m / z value range. Ions that are able to pass through the quadrupole mass filter 17 during this scan measurement are detected. Department Reached 18 and found Department The detector 18 outputs an ion intensity signal corresponding to the amount of ions that have reached the detector as a detection signal. The detection signal is digitized and then sent to the control and processing unit 2 and stored in the data storage unit 27.

[0033] After the analysis is completed, the compound identification unit 28 performs a process of identifying each target compound based on the collected data. Specifically, the compound identification unit 28 first obtains ion intensity data at the m / z value of the monitor ion for each target compound, and creates an extracted ion chromatogram. Note that this extracted ion chromatogram may be a waveform only in a predetermined time range including the retention time of the target compound. Then, the compound identification unit 28 detects a peak in the extracted ion chromatogram created, and obtains an actual mass spectrum at the retention time of the detected peak top. For example, if no significant chromatographic peak is detected in the extracted ion chromatogram, it is determined that the target compound is not included.

[0034] When the measured mass spectrum is obtained, the compound identification unit 28 acquires the mass spectrum of the target compound registered in the method file as a reference mass spectrum, and calculates the similarity between the pattern of the reference mass spectrum and the measured mass spectrum. The method for calculating this similarity may be a known method. Then, it is determined whether the similarity is equal to or greater than a predetermined threshold, and if the similarity is equal to or greater than the threshold, it is determined that the target compound is contained in the sample. Conversely, if the similarity is less than the threshold, it is determined that the target compound is not contained in the sample. In this way, it is possible to confirm whether all target compounds are contained in the sample, that is, to identify the target compounds (step S9).

[0035] The procedure for compound identification by the compound identification unit 28 can be changed as appropriate. For example, when an extracted ion chromatogram is created for a certain target compound and no peak is detected in the extracted ion chromatogram near the retention time of the target compound, the compound may exist but the peak may not be detected because other compounds overlap. Therefore, when the peak cannot be detected, an extracted ion chromatogram may be created at the m / z value of the reference ion of the target compound, and the compound may be identified using the peak detected in the extracted ion chromatogram.

[0036] Furthermore, instead of making a final compound identification based only on the similarity between the reference mass spectrum and the measured mass spectrum, the compound may also be identified by also using the ratio of the signal intensity of the monitor ion to the signal intensity of the reference ion in the measured mass spectrum, i.e., the confirmation ion ratio.

[0037] [Extraction of monitor ions from mass spectra] An example of the ion extraction process in step S4 will be described with reference to FIGS. The ion extraction unit 21 first detects mass peaks from the mass spectrum (step S11), and determines the intensity value of the mass peak showing the maximum intensity (step S12). In the example of the mass spectrum shown in Fig. 6, the mass peak indicated by the arrow P is the mass peak showing the maximum intensity, and its intensity value is Imax.

[0038] Next, the ion extraction unit 21 extracts mass peaks whose intensity value is 10% or more of the maximum intensity value from among all mass peaks detected in step S11 (step S13). This value of "10%" is an example and can be changed as appropriate. In the example of Fig. 6, the intensity value of Imax x 0.1 is indicated by a dashed dotted line A, and mass peaks whose peak intensity exceeds this are indicated by circles.

[0039] The ion extraction unit 21 selects the mass peak with the largest m / z value as a monitor ion from among the mass peaks extracted in step S13 (step S14). Furthermore, from among the mass peaks extracted in step S13, a predetermined number of mass peaks with m / z values ​​smaller than that of the monitor ion are selected as reference ions (step S15). If the number of reference ions is two, in the example of FIG. 6, the mass peak indicated by the arrow M is selected as the monitor ion, and the mass peaks indicated by the arrows R1 and R2 are selected as reference ions.

[0040] The reason why mass peaks having intensity values ​​greater than a certain level are selected as candidates for monitor ions and reference ions in steps S12 and S13 is to select ions with relatively high detection sensitivity as monitor ions and reference ions.

[0041] On the other hand, when an ionization method that easily generates fragments, such as the EI method, is used, the intensity of fragment ion peaks with small m / z values ​​tends to be high, and such mass peaks tend to overlap in multiple compounds with similar chemical structures. Therefore, if the mass peak with the highest intensity value is simply selected as the monitor ion, there is a high possibility that the monitor ions of multiple different compounds will overlap. On the other hand, the higher the m / z value of the mass peak, the more likely it is that it is an ion peak resulting from the desorption of protons from the compound molecule rather than a fragment ion peak. Therefore, as mentioned above, by selecting a mass peak with as large an m / z value as possible, it is possible to avoid the overlap of monitor ions of different compounds.

[0042] That is, by the processes in steps S14 and S15, it is possible to select monitor ions and reference ions that have a good balance between high detection sensitivity and compound selectivity. Alternatively, the procedure may be substantially reversed from the above process, and the monitor ion and reference ion may be determined by focusing only on mass peaks whose m / z values ​​are equal to or greater than a certain value, for example, m / z 50 or greater, and selecting mass peaks with high intensity values ​​from among those mass peaks. In this way, the monitor ion and reference ion can be appropriately determined by using both the m / z value and intensity value of the mass peak.

[0043] However, depending on the compound, there are cases where a certain fragment ion and its isotope ion are observed with high intensity, and if the above method is used as is, the ion peak of a certain fragment and its isotope ion peak will be selected as the monitor ion and reference ion. Even in such a case, there is almost no practical problem, but to avoid this, for example, it is advisable to exclude mass peaks that exist within a predetermined m / z value range (e.g., ±3, ±5 Da, etc.) with respect to the m / z value of the mass peak selected as the monitor ion from the selection of the reference ion.

[0044] In addition, the user may be allowed to set conditions for the ion extraction unit 21 to extract monitor ions from the mass spectrum. An example of this will be described. When the user performs a predetermined operation using the input unit 3, the ion extraction unit 21 displays a monitor ion extraction condition setting screen 6, an example of which is shown in Fig. 7, on the screen of the display unit 4. The user inputs two parameters, "m / z range" and "relative intensity range", in this monitor ion extraction condition setting screen 6, and presses the OK button. This makes it possible to limit the m / z value range for selecting monitor ions, and also to appropriately determine the intensity value threshold for selecting mass peaks.

[0045] As described above, in the GC-MS system of this embodiment, the m / z values ​​of the monitor ions and reference ions used for compound identification can be determined based on the mass spectrum of each compound recorded in the spectrum library without substantial burden on the user. Furthermore, the monitor ions determined for each compound in this way are unlikely to overlap with other compounds and are detected with high sensitivity, so that the compounds can be identified with high accuracy.

[0046] [Variations] In the GC-MS system of the above embodiment, the MS unit 1B is a single-type mass spectrometer. However, the MS unit 1B may be a mass spectrometer capable of MS / MS analysis, such as a triple quadrupole mass spectrometer or a quadrupole-time-of-flight mass spectrometer, or an MS where n is 3 or more, such as an ion trap mass spectrometer or an ion trap time-of-flight mass spectrometer. n When an MS / MS type mass spectrometer is used, the m / z values ​​of the monitor ion and the reference ion are replaced with a combination of the m / z value of the precursor ion and the m / z value of the product ion (i.e., MRM transition).

[0047] In the GC-MS system of the above embodiment, the MS unit 1B repeatedly performs scan measurements, but a selected ion monitoring (SIM) measurement targeting monitor ions and reference ions may be performed. In that case, compounds may be identified based on other information such as a confirmation ion ratio, rather than on the similarity of mass spectra.

[0048] Furthermore, although the above embodiment is an example in which the present invention is applied to a GC-MS, the present invention can also be applied to an LC-MS or SFC-MS. However, the above-mentioned process for extracting monitor ions and the like from a mass spectrum is premised on the fact that many fragment ions are generated during ionization in a mass spectrometer. Therefore, regardless of whether the upstream stage of the mass spectrometer is a GC, LC, or SFC, it is preferable that the ion source of the mass spectrometer is one that uses an ionization method that is likely to generate fragments (in other words, promotes fragmentation).

[0049] Furthermore, the above embodiment and various modified examples are merely examples of the present invention, and it is clear that any appropriate modifications, corrections, or additions made within the spirit of the present invention will be encompassed within the scope of the claims of the present application.

[0050] [Various aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0051] (Item 1) One aspect of the chromatographic mass spectrometer according to the present invention is A measurement unit including a chromatograph unit that separates compounds in a sample in the time direction and a mass spectrometer unit that detects each of the separated compounds; an ion extraction unit that acquires a mass spectrum of a target compound from a spectrum library that stores compound information including standard mass spectra and retention times or retention indices, and extracts monitor ions for each target compound using the intensities of mass peaks observed in the mass spectrum and mass-to-charge ratio values ​​corresponding to the mass peaks; a database creation unit that registers, in a database, compound information of the target compound and the mass-to-charge ratio value of the monitor ion extracted by the ion extraction unit; a compound specification receiving unit that receives specification by a user of a target compound to be analyzed from among the compounds registered in the database; a method creation unit that creates an analytical method for the target compound by using registered information in the database; A control unit that controls the operation of the measurement unit to perform chromatographic mass spectrometry on a target sample according to the analysis method; a compound identification unit that identifies a compound in the target sample by using a chromatographic mass spectrometry result for the target sample and the analysis method or registered information in the database; Equipped with.

[0052] In the chromatograph mass spectrometer described in paragraph 1, the mass-to-charge ratio of a monitor ion appropriate for identifying a target compound is automatically extracted and registered in an analysis database, without the user having to perform the tasks of analyzing a standard sample containing the target compound or extracting appropriate monitor ions from a mass spectrum obtained for the target compound. As a result, the chromatograph mass spectrometer described in paragraph 1 can identify a large number of compounds with high accuracy while reducing the burden of complicated tasks on the user in target analysis of a large number of compounds.

[0053] (Item 2) In the chromatographic mass spectrometer described in item 1, the compound identification unit may be configured to create an extracted ion chromatogram corresponding to a monitor ion for each target compound, and identify the compound by comparing a mass spectrum of a peak detected in the extracted ion chromatogram using a retention index or retention time with a mass spectrum included in the analysis method or registered information in the database.

[0054] The chromatographic mass spectrometer described in paragraph 1 can obtain monitor ions that have almost no overlap in mass-to-charge ratio value with monitor ions of other compounds. Therefore, in the extracted ion chromatogram created by the chromatographic mass spectrometer described in paragraph 2, chromatographic peaks corresponding to the target compound contained in a trace amount in the sample can be observed well, and compound identification can be performed using the measured mass spectrum in which ions derived from the target compound are sufficiently observed. This allows compound identification to be performed with high accuracy.

[0055] (Item 3) In the chromatographic mass spectrometer described in item 1 or 2, the ion extraction section may determine, as the mass-to-charge ratio value of the monitor ion, a mass-to-charge ratio value corresponding to a peak having the largest mass-to-charge ratio value among peaks having an intensity value equal to or greater than a predetermined value based on an intensity value of a peak showing the maximum intensity in the mass spectrum.

[0056] According to the chromatographic mass spectrometer described in the third aspect, it is possible to select monitor ions that have sufficiently high detection sensitivity and are unlikely to overlap in mass-to-charge ratio with ions derived from other compounds, that is, that have high compound selectivity, thereby improving the accuracy of compound identification when compound identification is performed using the monitor ions.

[0057] (Item 4) The chromatographic mass spectrometer described in item 3 may further include an extraction condition specification receiving unit that receives user specification of the intensity range and mass-to-charge ratio value range conditions when extracting monitor ions in the ion extraction unit.

[0058] According to the chromatographic mass spectrometer described in item 4, the user can appropriately set the conditions of the intensity range and the mass-to-charge ratio value range to select a monitor ion that is more appropriate in terms of both detection sensitivity and compound selectivity.

[0059] (Item 5) In the chromatographic mass spectrometer described in item 3, the mass analysis section may include an ion source using an ionization method that promotes fragmentation of ions.

[0060] A specific example of the ionization method that promotes ion fragmentation is electron ionization. When such an ionization method is used, fragment ion peaks from multiple compounds tend to overlap in a region of the mass spectrum where the mass-to-charge ratio is relatively small, whereas ion peaks from different compounds tend to be observed without overlapping in a region of the mass-to-charge ratio where the mass-to-charge ratio is relatively large. Therefore, according to the chromatographic mass spectrometer described in paragraph 5, as described above, when a mass-to-charge ratio value corresponding to a peak with a relatively large mass-to-charge ratio value is selected as the mass-to-charge ratio value of the monitor ion, the possibility that the monitor ion will overlap with other compounds can be reduced.

[0061] (Item 6) In the chromatographic mass spectrometer according to any one of items 1 to 5, the ion extraction unit extracts one or more reference ions in addition to the monitor ions for each target compound by utilizing an intensity of a mass peak observed in a mass spectrum of the target compound and a mass-to-charge ratio value corresponding to the mass peak; the database creation unit registers the mass-to-charge ratio value of the reference ion in a database; The compound identification section may use a ratio between an intensity at a mass-to-charge ratio value of a monitor ion and an intensity at a mass-to-charge ratio value of a reference ion for compound identification.

[0062] According to the chromatographic mass spectrometer described in item 6, for example, when the monitor ions are suspected to overlap with other compounds, an extracted ion chromatogram of a reference ion instead of the monitor ion can be created, and the compound can be identified using the chromatogram, thereby making it possible to more reliably identify the compound. [Explanation of symbols]

[0063] 1...Measuring part 1A…Gas chromatograph (GC) section 10...Sample vaporizer 11. Micro syringe 12…Column oven 13…Column 1B…Mass spectrometry (MS) section 14…Chamber 15…Ion source 16…Ion lens 17...Quadrupole mass filter 18…Detection section 2. Control and processing section 20...Library reading section 21...Ion extraction section 22…Database Creation Department 23…Target analysis database 24…Analysis method creation section 25…Analysis method storage section 26...Analysis control section 27...Data storage section 28…Compound Identification Section 3. Input section 4...Display section 5. Spectral Library

Claims

1. A measurement unit including a chromatograph unit that separates compounds in a sample in the time direction and a mass spectrometer unit that detects each of the separated compounds; an ion extraction unit that acquires a mass spectrum of a target compound from a spectrum library that stores compound information including standard mass spectra and retention times or retention indices, and extracts monitor ions for each target compound using the intensities of mass peaks observed in the mass spectrum and mass-to-charge ratio values ​​corresponding to the mass peaks; a database creation unit that registers, in a database, compound information of the target compound and the mass-to-charge ratio value of the monitor ion extracted by the ion extraction unit; a compound specification receiving unit that receives specification by a user of a target compound to be analyzed from among the compounds registered in the database; a method creation unit that creates an analytical method for the target compound by using registered information in the database; A control unit that controls the operation of the measurement unit to perform chromatographic mass spectrometry on a target sample according to the analysis method; a compound identification unit that identifies a compound in the target sample by using a chromatographic mass spectrometry result for the target sample and the analysis method or registered information in the database; A chromatography mass spectrometer comprising:

2. 2. The chromatography mass spectrometer according to claim 1, wherein the compound identification unit creates an extracted ion chromatogram corresponding to a monitor ion for each target compound, and identifies the compound by comparing a mass spectrum of a peak detected in the extracted ion chromatogram using a retention index or a retention time with a mass spectrum included in the analysis method or the registered information in the database.

3. 2. The chromatographic mass spectrometer according to claim 1, wherein the ion extraction unit determines, as the mass-to-charge ratio value of the monitor ion, a mass-to-charge ratio value corresponding to a peak having a largest mass-to-charge ratio value among peaks having an intensity value equal to or greater than a predetermined value based on an intensity value of a peak showing a maximum intensity in the mass spectrum.

4. 4. The chromatography mass spectrometer according to claim 3, further comprising an extraction condition specification receiving section that receives user specifications regarding conditions of an intensity range and a mass-to-charge ratio value range when the monitor ions are extracted by the ion extraction section.

5. 4. The chromatographic mass spectrometer according to claim 3, wherein the mass analysis section includes an ion source using an ionization method that promotes fragmentation of ions.

6. the ion extraction unit extracts one or more reference ions in addition to the monitor ions for each target compound by utilizing the intensities of mass peaks observed in the mass spectrum of the target compound and mass-to-charge ratio values ​​corresponding to the mass peaks; the database creation unit registers the mass-to-charge ratio value of the reference ion in a database; 2. The chromatography mass spectrometer according to claim 1, wherein the compound identification section uses a ratio between an intensity at a mass-to-charge ratio value of a monitor ion and an intensity at a mass-to-charge ratio value of a reference ion for compound identification.

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