JP4905265B2 - Data processor for chromatograph mass spectrometer - Google Patents

Description

The present invention relates to a data processing apparatus that processes data collected by a chromatograph mass spectrometer such as a gas chromatograph mass spectrometer (GC / MS) or a liquid chromatograph mass spectrometer (LC / MS). An MS ^n- type mass spectrometer capable of repeating cleavage / mass analysis multiple times, selecting ions with a specific mass-to-charge ratio as precursor ions, cleaving them, and mass-analyzing the product ions generated thereby, was used. The present invention relates to a data processing apparatus for a chromatograph mass spectrometer.

The liquid chromatograph mass spectrometer (LCMS-IT-TOF manufactured by Shimadzu Corporation) described in Non-Patent Document 1 is an ion trap for temporarily holding ions and sorting them according to their mass before causing cleavage. IT) and a time-of-flight mass spectrometer (TOF-MS) for mass-analyzing ions ejected from the ion trap with high mass resolution and accuracy, and the MS obtained during the LC / MS analysis The presence or absence of an ion to be selected as a precursor ion (hereinafter, the precursor ion selected based on the MS spectrum is referred to as a main precursor ion) is determined from the spectrum, and when the ion is present, the ion is set as the precursor ion. MS / MS (= MS ² ) analysis is performed, and the presence or absence of ions to be further selected as precursor ions is determined from the MS ² spectrum. , And a function that can automatically repeat the target ion cleavage and mass spectrometry (this function is called an auto MS ⁿ function).

  The selection of the precursor ion is determined depending on whether or not it matches a preset selection condition such as one having a peak intensity equal to or higher than a predetermined threshold value, or one having a predetermined mass range. Therefore, whether or not the main precursor ion is selected from the MS spectrum, or how many main precursor ions are selected depends on the precursor ion selection conditions, the concentration of the sample, the intensity of the actually acquired spectrum, etc. To do. Therefore, it is impossible to know how many main precursor ions are detected in the process of collecting data of LC / MS analysis before the analysis.

In addition, the number of MS ⁿ spectra acquired from the main precursor ion selected based on the MS spectrum is not determined, and the number increases with the passage of time from the sample injection in the liquid chromatograph. Change. Briefly described with reference to FIG. 2, when a total ion chromatogram (TIC) is obtained as shown in FIG. 2A, for example, at time t1, there is no peak selected as a precursor ion on the MS spectrum. Therefore, an MS ⁿ spectrum with n = 2 or more cannot be obtained. In contrast, at time t2, there is a peak (m / z = M1) selected as a precursor ion on the MS spectrum, and it is also selected as a precursor ion on the MS ² spectrum obtained by cleaving the precursor ion. Therefore, an MS ³ spectrum is obtained by further cleaving the precursor ion. As a result, MS ² and MS ³ spectra can be obtained in addition to the MS spectrum.

  By the way, use this when you want to print out the analysis results such as the MS spectrum obtained as described above on paper, or when you want to create an electronic file in the same format as the printed output. It is desirable that the format be easy to see and use, and it is important that such printed information is easy to manage. Further, depending on the case, the number of main precursor ions may be several hundred or more for one sample, and it is necessary to reduce the cost by reducing the number of papers as much as possible, especially when printing on paper.

Conventionally, for example, Patent Document 1 discloses that an MS spectrum and MS ² , MS ³ , and MS ⁴ spectra derived from one main precursor ion existing in the MS spectrum are displayed side by side. If this display is printed on a sheet of paper as it is, a spectrum derived from one main precursor ion should be printed per page.

  However, in the case of a liquid chromatograph mass spectrometer (the same applies to a gas chromatograph mass spectrometer), there is insufficient information in the above format. That is, if the separation state by chromatography is not good and the target component is not isolated, the quality of the collected MS spectrum is poor, and qualitative and quantitative based on this is likely to lack accuracy. However, even if you look at the printed screen of the conventional technology as described above, you cannot immediately confirm the separation status of the target component that is the source of the main precursor ion being analyzed. It is necessary to check mass chromatograms corresponding to the mass-to-charge ratios of the precursor ions one after another, resulting in poor working efficiency.

Further, as described above, the number of precursor ions obtained by one LC / MS analysis is enormous, and the number of MS spectra derived from one precursor ion is also various. For this reason, in the conventional method of printing the display screen as it is, the printed material becomes too large, the printing cost becomes very high, and it is difficult to manage. In order to reduce the number of sheets used and print with good appearance, the operator must adjust the print layout by displaying the MS ⁿ spectrum related to each main precursor ion one by one on the display screen. However, when there are a large number of target main precursor ions, this is a difficult task, and mistakes are likely to occur.

JP-A-10-293120 “Liquid Chromatograph Mass Spectrometer LCMS-IT-TOF”, [online], Shimadzu Corporation, [Search June 11, 2007], Internet <URL: http://www.an.shimadzu.co. jp / products / lcms / it-tof.htm>

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a useful document that allows a user to easily determine the accuracy of an MS ⁿ spectrum. The object is to provide a data processing apparatus for a mass spectrometer. A second object of the present invention is to provide a data processing apparatus for a chromatograph mass spectrometer that can provide useful materials that are easy for the user to see and manage.

In order to solve the above problems, the present invention provides a chromatograph that separates components of a sample, and a specific mass-to-charge ratio based on an MS spectrum obtained by mass spectrometry of the sample separated by the chromatograph. MS ^n- type (n is an integer greater than or equal to 2) mass spectrometer that repeats the cleaving operation and mass analysis for the precursor ion at most n-1 times. In a data processing device for processing data acquired by the device,
a) an input means for the user to input precursor ion selection conditions;
b) In the data acquired by the chromatograph mass spectrometer, a precursor ion that matches the selection conditions input by the input means is extracted, and an MS spectrum in which the peak of the precursor ion appears, and the precursor ion Data collecting means for collecting data constituting all of the MS ^m spectra derived from (where m is an integer from 2 to n ) and a mass chromatogram of the precursor ion in mass-to-charge ratio,
c) means for outputting data so that the MS spectrum, all MS ^m spectra, and mass chromatograms collected by the data collecting means are printed side by side as related information of one precursor ion ; Depending on the number of MS spectra, all MS ^m spectra, and mass chromatograms contained in the relevant information of one precursor ion to be printed on the print area set on the size paper , the print area is adaptive. Output control means to divide into
It is characterized by having.

According to the data processor for a chromatograph mass spectrometer according to the present invention, it is possible to select and print only the relevant information of the necessary main precursor ions, so that the number of sheets used for printing the analysis result Can be reduced. Further, since unnecessary results are not printed, it is possible to improve the efficiency of the work itself for checking the results.
In the data processing apparatus for a chromatograph mass spectrometer according to the present invention, for example, a mass chromatogram is printed at the top of the assigned print area, an MS spectrum is printed below, and further below. It is preferable to print the MS ² spectrum, the MS ³ spectrum,. Moreover, it is good to print over the symbol which shows the time position where MS spectrum was acquired on the mass chromatogram. According to this, the mass chromatogram at the mass-to-charge ratio of the main precursor ion used for the analysis after MS ² in the MS spectrum is printed in the same print area, so the user can determine the peak shape and retention time by chromatography. Thus, it can be easily determined whether or not the MS ⁿ spectrum derived from the main precursor ion is normally or appropriately acquired. Therefore, the utility value as a material is high, and the efficiency of analysis work can be promoted.

Further, in the data processing apparatus according to the present invention, the size of the print area is constant regardless of the number of MS ⁿ spectra, and if the number of MS ⁿ spectra to be recorded in the print area is large, the allocated area size per spectrum If the number of MS ⁿ spectra to be recorded is small, adjustment is automatically made so that the allocated area size per spectrum becomes large. Note that the area size where the mass chromatogram is arranged may be fixed for easy viewing.

According to this, even if the number of main precursor ions to be printed increases, the related information of each main precursor ion is printed in the print area placed at the determined size and position on the paper surface. It is easy for the user to see and manage. Further, by increasing the printing area provided on one sheet, the number of sheets used for printing the result of one sample is reduced, so that the printing cost can be reduced and the management becomes easy.
Note that the number and size of the print areas set on one sheet of paper may be determined in advance, but can be determined by the user arbitrarily or by selecting from previously prepared options. This is preferable.
Further, in the data processing apparatus for a chromatograph mass spectrometer according to the present invention, the output control means sets related information of a plurality of precursor ions obtained by analyzing the same sample on a sheet of a predetermined size. It is preferable that data output be performed so that printing is sequentially performed on one or a plurality of print areas.

  An embodiment of a liquid chromatograph mass spectrometer to which a data processing apparatus according to the present invention is applied will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a liquid chromatograph mass spectrometer according to this embodiment.

  In the liquid chromatograph (LC unit) 3, the mobile phase stored in the mobile phase container 30 is sucked at a substantially constant flow rate by the liquid feed pump 31 and fed to the column 33. A sample to be analyzed is introduced into the mobile phase from the injector 32 at a predetermined timing, and is sent to the column 33 on the mobile phase. While passing through the column 33, various components contained in the sample are separated in the time direction and eluted in order from the column 33. The sample solution containing the eluted sample components is introduced into the mass spectrometer (MS unit) 1.

  The sample liquid is sprayed from the electrospray nozzle 10 into the ionization chamber 11 which is an atmosphere of substantially atmospheric pressure, whereby the component molecules in the sample liquid are ionized, and the generated ions pass through the heating pipe 12 and have a low vacuum atmosphere. It is fed into the first intermediate vacuum chamber 13. In the ionization chamber 11, in addition to electrospray ionization, another atmospheric pressure ionization method such as atmospheric pressure chemical ionization may be employed, or they may be used in combination. In any case, the ions are converged by the first ion lens 14 disposed in the first intermediate vacuum chamber 13 and sent to the second intermediate vacuum chamber 15 that is an intermediate vacuum atmosphere. While being converged by the second ion lens 16 arranged, it is fed into the analysis chamber 17 which is a high vacuum atmosphere.

  In the analysis chamber 17, the ions are temporarily accumulated in the ion trap 18, and in some cases, subjected to mass separation (mass selection) and cleavage operation, and are discharged from the ion trap 18 at a predetermined timing and are time-of-flight type. It is introduced into the mass separator 19. The operation of ions in the ion trap 18 is controlled by the voltage applied from the IT power supply unit 26 to each electrode (end cap electrode, ring electrode).

  The time-of-flight mass separator 19 is a reflectron type including a reflectron 20 that reflects ions by an electrostatic field, and ions are separated according to mass (strictly, mass-to-charge ratio m / z) during the return flight. The ions with smaller mass reach the ion detector 21 earlier. The ion detector 21 is composed of, for example, a combination of a conversion dynode that converts ions into electrons and a secondary electron multiplier, and outputs a detection signal corresponding to the amount of ions that have reached. This detection signal is converted into a digital value by the A / D converter 22 and input to the data processing unit 23. The data processing unit 23 creates a mass spectrum, a mass chromatogram, and a total ion chromatogram, and qualitatively based on the results. Analysis and quantitative analysis are performed.

  Further, an operation unit 27 such as a keyboard and a mouse, a display unit 28 such as an LCD display, and a printing unit 29 that is a printer are connected to the control unit 25 that controls each unit in order to execute the mass spectrometry operation as described above. ing. The entity of the data processing unit 23 and the control unit 25 is a personal computer, and functions as the data processing unit 23 and the control unit 25 are exhibited by executing a dedicated control / processing program installed in the personal computer. Is done.

In the MS unit 1, normal MS analysis can be performed simply by accumulating and extracting ions in the ion trap 18, while n−1 ion mass selection and collision-induced dissociation (CID) are performed in the ion trap 18. MS ⁿ analysis can be performed by performing an ion cleavage operation according to). In order to perform collision-induced dissociation, a collision gas such as Ar gas is supplied into the ion trap 18 from a gas supply means (not shown).

Next, an auto MS ⁿ function that can be performed in the liquid chromatograph mass spectrometer will be described with reference to FIG.

  FIG. 2A shows a part of a total ion chromatogram created when LC / MS is executed. This is a plot of the detection results (intensity values) of all ions regardless of mass with the passage of time. Actually, MS analysis is executed at a predetermined time interval, and one MS analysis is performed for each MS analysis. A mass spectrum (MS spectrum) is created.

In the auto MS ⁿ function, it is immediately determined whether or not the peak intensity of the peak appearing in the MS spectrum meets a preset condition. If there is a matching peak, the ion corresponding to the peak is automatically set as the main precursor ion, mass separation is performed so that the ion is selected by the ion trap 18, and the selected A cleavage operation is performed to cause ions to be collision-induced dissociation. Various product ions generated by the cleavage are introduced into the time-of-flight mass separator 19 and separated by mass, and detected by the ion detector 21. Based on the detection result, the data processor 23 creates an MS ² spectrum.

Furthermore, for peaks appearing in the MS ² spectrum, it is determined whether or not the peak intensity meets the preset conditions. If there is a matching peak, the ion corresponding to that peak is automatically used as the precursor ion. The ion trap 18 performs the second selection and cleavage operation of the precursor ion subsequent to the first cleavage operation. Then, various product ions generated by the cleavage are introduced into the time-of-flight mass separator 19, mass-separated, and detected by the ion detector 21. Based on the detection result, the data processing unit 23 creates an MS ³ spectrum. Such selection and cleavage of the precursor ions are repeated until there is no peak that meets the set conditions, with a predetermined value of n as the upper limit.

In FIG. 2 (a), at time t1, since the main precursor ion does not exist on the MS spectrum, analysis after MS ² is not performed (see FIG. 2 (b)), while at time t2, the main spectrum ion is not detected on the MS spectrum. Since the precursor ion was present, MS ² analysis was performed, and further, because the precursor ion was also present on the MS ² spectrum, MS ³ analysis was performed (see FIG. 2C).

In the example of FIG. 2, one main precursor ion is selected. However, when a plurality of peaks meet the set conditions, there are a plurality of main precursor ions. , MS ² analysis is performed, and MS ² or a subsequent spectrum is created.

In practice, it is possible to create an MS ⁿ spectrum with a good S / N ratio by repeating MS ⁿ analysis with the same precursor ion as many times as necessary and integrating the resulting mass profiles. It is.

As described above, if the auto MS ⁿ function is used, the peak of the target component is captured from the MS spectrum obtained near the elution time when the target component is eluted for one sample injection in the LC unit 3. It is possible to automatically acquire an MS ⁿ spectrum reflecting the structure and composition of the component.

The enormous amount of data acquired for one sample injection in this way is stored as one data file in the data storage unit 24 such as a hard disk drive. As described above, when the precursor ion is set during the LC / MS analysis and the MS ⁿ analysis is executed, not only the mass and peak intensity of the precursor ion but also information such as the ion valence and polarity are also included. To be recorded. The data processing unit 23 performs qualitative analysis using the data in the data file to identify the target component, performs structural analysis of the target compound, and examines the concentration and content of the target component by quantitative analysis. can do.

  Next, a data printing process that is executed mainly by the control unit 25 and the data processing unit 23, which is a feature of the liquid chromatograph mass spectrometer of the present embodiment, will be described with reference to FIGS. FIG. 3 is a flowchart showing a procedure of the data printing process, FIG. 4 is a schematic explanatory diagram of a print layout, and FIG. 5 is a diagram showing a print example.

  First, prior to executing the printing process, the operator (user) inputs selection conditions for the main precursor ion for printing from the operation unit 27 (step S1). This selection condition includes, for example, one of the mass range of the main precursor ion, the time range in which the main precursor ion appears, the ion valence of the main precursor ion, the polarity of the main precursor ion, the peak intensity of the main precursor ion, and the like. Or it can be a plurality of combinations.

  The operator also inputs a print layout condition from the operation unit 27 (step S2). The conditions of this print layout are the size of the paper (paper surface) to be printed, the number of precursor ion related information posted on the paper surface of one page (that is, the number of print regions 41 described later), For example, the height of the mass chromatogram printing area 42 in FIG. Here, as an example, it is assumed that the paper size is A4 size portrait, and two printing areas 41 each having a height H1 are provided on the top and bottom of the paper surface 40 of one page as shown in FIG. Further, it is assumed that the height of the mass chromatogram print area 42 set at the upper part in each print area 41 is H2.

  When the printing process is started by the operation of the operator, the data processing unit 23 obtains information on the main precursor ion based on the MS spectrum (the mass of the precursor ion, the time of appearance, the ion from the data file stored in the data storage unit 24). A list of precursor ions is created by collecting valence, polarity, peak intensity, and the like (step S3). Next, main precursor ions that match the selection conditions set in step S1 are extracted from the created list (step S4). There may be a case where no main precursor ion is extracted, but here, a case where at least one main precursor ion is extracted will be considered.

For one extracted main precursor ion, the data constituting the MS ² spectrum obtained by cleaving the main precursor ion is read from the data file in the data storage unit 24 (step S5). Next, it is checked whether or not the precursor ion is included in the MS ² spectrum (step S6). If the precursor ion is included, the MS ³ spectrum obtained by cleaving the precursor ion should be present. Returning to step S5, the data constituting the MS ³ spectrum is read from the data file in the data storage unit 24. Steps S5 and S6 are repeated, for example, at the beginning, that is, until there is no MS ⁿ spectrum derived from the main precursor ion based on the MS spectrum.

When the collection of the MS ⁿ spectrum data derived from one main precursor ion is completed in this way, the data constituting the mass chromatogram corresponding to the mass-to-charge ratio of the main precursor ion is now stored in the data storage unit 24. Is read from the data file (step S7). For example, if the mass-to-charge ratio of the main precursor ion is 200, the configuration data of the mass chromatogram obtained by plotting the ion intensity signal of the mass-to-charge ratio 200 from the analysis start time to the analysis end time is read.

As a result, one or a plurality of MS ⁿ spectra related to one main precursor ion and one mass chromatogram are prepared, so that the spectrum printing region is divided according to the number of the MS ⁿ spectra and one spectrum is obtained. The height of the area to be printed is determined (step S8). Specifically, for each of the two print areas 41 provided on one sheet of paper 40 shown in FIG. 4, the range of the upper height H2 of the height H1 is the mass chromatogram print area 42. There is a region H <b> 3 below that is a spectral printing region 43. By dividing the spectrum print area 43 by the number of MS ⁿ spectra in the height direction, an area per spectrum is determined. For example, if there are ^three spectra up to the MS ³ spectrum, a range obtained by dividing the height H3 into three is set as a region assigned to one spectrum.

When the print area is determined, the printing unit 29 prints one mass chromatogram in the mass chromatogram print area 42 and one or more MS ⁿ spectra in the spectrum print area 43 in descending order from n = 1. The data is output to (Step S9). As a result, the printing unit 29 performs printing on the upper or lower printing area 41 on the prepared paper surface 40. When printing is started, the data processing unit 23 determines whether or not the printing process for all the precursor ions extracted in step S4 has been completed (step S10), and the printing process has not been performed yet, that is, the processes in steps S5 to S9. If there is a main precursor ion that has not been subjected to the process, the process returns to step S5, and the above-described process for the unprocessed main precursor ion is repeated.

The related information of the main precursor ions that are sequentially processed, that is, the mass chromatogram and the MS ⁿ spectrum, are the upper print area of one sheet 40 → the lower print area → the upper print area of the next sheet 40. Printing is continuously performed in the order of → lower print area →. Then, if the related information of all the extracted main precursor ions is printed, it is determined as Yes in step S10, and the process ends.

FIG. 5 is a diagram showing an example of printing on one sheet of paper. In the upper printing area 41 on the sheet 40, the precursor information obtained up to the MS ² spectrum is obtained, and in the lower printing area 41, the MS is displayed. Precursor information obtained up to ⁴ spectra is posted. As the number of MS spectra increases, the height per spectrum decreases, so that the shape is reduced in the vertical direction. As the number of printed spectra increases in this way, the number of precursor information printed on one sheet of paper is constant, and as a result, the position of the print area or mass chromatogram print area on the sheet for each precursor. Is easy to see and manage.

  In addition, a downward arrow symbol is displayed at the time each precursor ion appears on the mass chromatogram, so that the component separation state at the position where the precursor ion appears can be confirmed at a glance. For example, if there is no peak in the mass chromatogram at the position where this downward arrow symbol is present, it is immediately apparent that there is an abnormality in the detection of the precursor ion. Moreover, when it is an overlapping part of two or more peaks on the mass chromatogram, it can be recognized that the mass spectrum may contain a plurality of components.

  If the number of print areas provided on one sheet of paper 40 is increased to 3, 4,... By changing the print layout condition setting, the precursor information posted on one page increases to 3, 4,. This is useful when you want to reduce the number of paper used. Of course, by making the precursor ion selection conditions more strict, the number of sheets of paper used can be reduced by reducing the number of precursor ions to be printed.

  It should be noted that each of the above-described embodiments is merely an example, and it is obvious that modifications, changes, and additions are appropriately included in the scope of the claims of the present application within the scope of the present invention. For example, in the above embodiment, the present invention is applied to LC / MS, but the present invention can be similarly applied to GC / MS.

The schematic block diagram of LC / MS by one Example of this invention. Illustration of the auto MS ⁿ function in LC / MS of the present embodiment. The flowchart which shows the procedure of the data printing process in LC / MS of a present Example. Explanatory drawing of a printing layout. The figure which shows the example of printing on 1 sheet of paper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MS part 10 ... Electrospray nozzle 11 ... Ionization chamber 12 ... Heating pipe 13 ... 1st intermediate | middle vacuum chamber 14 ... 1st ion lens 15 ... 2nd intermediate | middle vacuum chamber 16 ... 2nd ion lens 17 ... Analysis chamber 18 ... Ion Trap 19 ... Time-of-flight mass separator 20 ... Reflectron 21 ... Ion detector 22 ... A / D converter 23 ... Data processing unit 24 ... Data storage unit 25 ... Control unit 26 ... IT power supply unit 27 ... Operation unit 28 ... Display unit 29 ... Printing unit 3 ... LC unit 30 ... Mobile phase container 31 ... Liquid feed pump 32 ... Injector 33 ... Column 40 ... Paper surface 41 ... Print area 42 ... Mass chromatogram print area 43 ... Spectrum print area

Claims (3)

The ion having a specific mass-to-charge ratio is selected as a precursor ion based on a chromatograph that separates the sample into components and the MS spectrum obtained by mass spectrometry of the sample separated in the chromatograph, and the precursor ion In a data processing apparatus for processing data acquired by a chromatograph mass spectrometer having an MS ^n- type (n is an integer of 2 or more) mass spectrometer that repeats cleavage operation and mass spectrometry at most n-1 times,
a) an input means for the user to input precursor ion selection conditions;
b) In the data acquired by the chromatograph mass spectrometer, a precursor ion that matches the selection conditions input by the input means is extracted, and an MS spectrum in which the peak of the precursor ion appears, and the precursor ion Data collecting means for collecting data constituting all of the MS ^m spectra derived from (where m is an integer from 2 to n ) and a mass chromatogram of the precursor ion in mass-to-charge ratio,
c) means for outputting data so that the MS spectrum, all MS ^m spectra, and mass chromatograms collected by the data collecting means are printed side by side as related information of one precursor ion ; Depending on the number of MS spectra, all MS ^m spectra, and mass chromatograms contained in the relevant information of one precursor ion to be printed on the print area set on the size paper , the print area is adaptive. Output control means to divide into
A data processing apparatus for a chromatograph mass spectrometer, comprising: The output control means includes an MS included in the related information of one precursor ion to be printed in the printing area. ^m Regardless of the number of spectra, the size of the mass chromatogram print area is determined, and the other spectrum print areas are designated as MS spectra and MS ^m The data processing apparatus for a chromatograph mass spectrometer according to claim 1, wherein the data is divided according to the total number of spectra. The output control means outputs data so that related information of a plurality of precursor ions obtained by analyzing the same sample is sequentially printed on one or a plurality of printing areas set on a predetermined size of paper. The data processing apparatus for a chromatograph mass spectrometer according to claim 1 or 2 .

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