WO2025004999A1 - Data processing device, mass spectrometry system, and mass spectrometry data processing method - Google Patents

Abstract

In order to enable highly accurate mass spectrometry, this mass spectrometry system comprises: a plot processing unit (212) that plots quadrupole RF voltage acquired as a result of measuring a plurality of calibration ions, for which m/z is known, using a mass spectrometer (100) and m/z of each of the calibration ions as calibration points at coordinates having quadrupole RF voltage and m/z as coordinate axes; a correction processing unit (213) that corrects the calibration points by correcting an outlier if there is an outlier with respect to the calibration points; and a measurement processing unit (213) that measures the calibration ions using the mass spectrometer (100) in a scan range centered on the quadrupole RF voltage calculated using the corrected calibration points.

Description

Data processing device, mass spectrometry system and mass spectrometry data processing method

The present invention relates to a data processing device, a mass spectrometry system, and a mass spectrometry data processing method.

In a mass spectrometer, ions with a known m/z are measured and the relationship between a specific parameter (the voltage applied to the electrodes in a quadrupole mass filter) and m/z is determined. When measuring a sample with an unknown m/z, the m/z is determined by using such techniques.

Patent Document 1 discloses a mass analysis control device, a mass analysis device, a mass analysis control method, and a mass analysis method, in which "an ionization control unit 1 controls an ionization unit 21 so as to ionize the analytical sample and the mass calibration sample into analytical sample ions and mass calibration sample ions. An ion dissociation control unit 2 controls an ion trap 23 so as to trap the analytical sample ions and mass calibration sample ions and selectively dissociate the mass calibration sample ions into a plurality of calibration fragment ions without selecting the analytical sample ions as precursor ions. An analysis control unit 3 controls a mass analyzer 24 so as to perform mass analysis of the analytical sample ions and the plurality of calibration fragment ions. In a mass analysis spectrum obtained by mass analysis, the mass-to-charge ratio of the analytical sample ions is calibrated by a calibration unit 4 based on the mass-to-charge ratios of the plurality of calibration fragment ions" (see abstract).

Patent document 2 discloses a method for measuring mass spectra under multiple conditions with different ionization polarities, etc., and performing mass axis calibration if there is a difference from the reference data.

JP 2019-86467 A US Patent Application Serial No. 2022/0246412

The problem that this invention aims to solve is to determine an accurate mass axis when performing mass axis calibration, even when there are impurity ions whose m/z values are adjacent to the calibration point.

In the technology described in Patent Document 1, sample ions and impurity ions coexist, so if the m/z of the calibration fragment ion and the impurity ion are adjacent, the peaks may be confused and an accurate mass axis may not be determined.

In the technology described in Patent Document 2, when the m/z of the calibration sample ion and the m/z of the impurity ion are adjacent, it is not possible to determine which of the adjacent spectral peaks is the calibration sample ion. Therefore, even if the technology described in Patent Document 2 can detect an abnormality from the difference with the reference data, it is not possible to be certain that it is a calibration sample ion.

The present invention was made in light of this background, and its objective is to enable highly accurate mass analysis.

In order to solve the above-mentioned problems, the present invention comprises a plot processing unit that plots a voltage obtained as a result of measuring a plurality of calibration ions, whose m/z is known, using a mass spectrometer, and the m/z of each calibration ion as calibration points on a coordinate system having the voltage and the m/z as coordinate axes, and a correction processing unit that corrects the calibration points by correcting the outliers if there are any outliers for each of the calibration points.
Other solutions will be described in the embodiments as appropriate.

The present invention makes it possible to perform mass analysis with high accuracy.

1 is a diagram illustrating an example of the configuration of a mass spectrometry system according to a first embodiment. FIG. 2 illustrates an example of a hardware configuration of a data processing device. FIG. 1 is a diagram showing the configuration of a quadrupole mass filter (part 1). FIG. 2 is a diagram showing the configuration of a quadrupole mass filter (part 2). FIG. 13 illustrates the operation of a quadrupole mass filter and the relationship between the quadrupole RF voltage and the quadrupole DC voltage. FIG. 1 is a graph showing the relationship between the quadrupole RF voltage and the ion signal intensity. FIG. 1 is a graph showing the relationship between m/z and quadrupole RF voltage (part 1). FIG. 2 is a graph showing the relationship between m/z and quadrupole RF voltage (part 2). FIG. 3 is a graph showing the relationship between m/z and quadrupole RF voltage (part 3). 3 is a flowchart showing the procedure of a mass spectrometry data processing method according to the first embodiment. FIG. 13 is a table showing specific values of calibration points. FIG. 13 is a graph showing deviations. FIG. 13 is a diagram illustrating a voltage calibration technique. 10 is a flowchart showing the procedure of a mass spectrometry data processing method according to a second embodiment. FIG. 4 shows a graph of the relationship between m/z and quadrupole RF voltage. FIG. 13 is a diagram illustrating an example of the configuration of a mass spectrometry system according to a third embodiment.

Next, a form for implementing the present invention (referred to as an "embodiment") will be described in detail with reference to the drawings as appropriate.

First Embodiment
[Mass spectrometry system 1]
FIG. 1 is a diagram showing an example of the configuration of a mass spectrometry system 1 according to the first embodiment.
The mass spectrometry system 1 includes a mass spectrometry device 100, a voltage control device 300, DC power supplies 301 and 303, and an RF power supply 302. The mass spectrometry system 1 further includes a data processing device 200 to which an output device 201 is connected. Incidentally, in Fig. 1, the dashed lines connecting the voltage control device 300 and the DC power supplies 301 and 303, the RF power supply 302, and the data processing device 200, and the dashed line connecting the detector 152 and the data processing device 200 indicate signal lines. In addition, the solid line connecting the DC power supply 303 and the ion guide 130, and the solid lines connecting the RF power supply 302 and the quadrupole mass filter 140 and the DC power supply 301 indicate electric wires to which voltages are applied.

The mass spectrometer 100 includes an ion source 151 , a first differential pumping section 101 , a second differential pumping section 102 , and an analyzing section 103 .
Ions generated in the ion source 151 are introduced into the first differential pumping section 101 through the aperture 121. The ion source 151 is composed of an electrospray ion source, an atmospheric pressure chemical ion source, an atmospheric pressure photoion source, an atmospheric pressure matrix-assisted laser desorption ion source, or the like, and operates at atmospheric pressure or at a vacuum lower than atmospheric pressure.

The first differential pumping section 101 is evacuated by a pump 111. As a result, the first differential pumping section 101 is maintained at a vacuum level of 10 Pa to 500 Pa. Ions that pass through the first differential pumping section 101 are introduced into the second differential pumping section 102 through an aperture 122. The second differential pumping section 102 is evacuated by a pump 112. As a result, the second differential pumping section 102 is maintained at a vacuum level of 0.1 Pa to 10 Pa. An ion guide 130 that focuses ions is installed in the second differential pumping section 102. Ions focused by the ion guide 130 are introduced through an aperture 123 into the analysis section 103 in which a quadrupole mass filter 140 is installed.

The ion guide 130 is supplied with a static voltage (hereinafter referred to as DC voltage) from a DC power supply 303. The RF power supply 302 applies a composite wave of the radio frequency voltage (hereinafter referred to as RF voltage) generated by the RF power supply 302 and the DC voltage sent from the DC power supply 301 to the quadrupole mass filter 140.

Also, as shown in FIG. 1, the ion guide 130 and the quadrupole mass filter 140 are connected via a dielectric 153 such as a capacitor. As described above, RF voltage is supplied to the quadrupole rod electrodes 141 (see FIGS. 3A and 3B) of the quadrupole mass filter 140 from an RF power supply 302 controlled by a voltage control device 300. The high-frequency component of the RF voltage is then supplied from the quadrupole rod electrodes 141 to the ion guide rod electrodes of the ion guide 130 through the dielectric 153. With this configuration, the number of power supplies can be reduced compared to a configuration in which RF voltage is supplied separately to the ion guide 130 and the quadrupole mass filter 140, making the mass spectrometry system 1 less expensive.

The analytical section 103 is evacuated by the pump 113. This keeps the analytical section 103 at a pressure of 1E-3 Pa or less. In the quadrupole mass filter 140, ions are separated according to m/z.

Ions that pass through the quadrupole mass filter 140 are detected by the detector 152. As the detector 152, an electron multiplier tube, a type that combines a scintillator and a photomultiplier tube, or a multichannel plate can generally be used. The detection intensity of the ions detected by the detector 152 is converted into an electrical signal (output signal) and sent to the data processing device 200. At this time, the output signal output from the detector 152 is converted into digital data with a fixed sampling period (typically 1 μs to 1000 μs) and then sent to the data processing device 200. The conversion to digital data is performed by an analog-to-digital converter (ADC) not shown or a pulse counting unit not shown. The data processing device 200 stores the sent digital data in the memory unit 220.

In the data processing device 200, in addition to the storage unit 220, a plot processing unit 211, a correction processing unit 212, and a measurement processing unit 213 are executed.
The plot processing unit 211 plots the calibration points 521 (FIGS. 6 to 7B) on the m/z-quadrupole RF voltage relationship graphs shown in FIGS. 6 to 7B.
The correction processing unit 212 corrects the calibration points 521 based on the calibration points 521 plotted by the plot processing unit 211 .
The measurement processing unit 213 controls the measurement by the mass spectrometer 100 .

The storage unit 220 is made up of a memory, HD, etc., and can store and hold information such as the data of the spectrum 501 (see FIG. 5), as well as numerical values and relational expressions required for correction. The plot processing unit 211, correction processing unit 212, and measurement processing unit 213 each have a calculation function and temporary memory for temporarily storing numerical values required for calculation. Furthermore, in addition to storing and converting this information, the data processing device 200 also has a function to control the voltage control device 300 that controls each electrode, etc., and a function to output information to the output device 201. The output device 201 is made up of a display, printer, etc. The output device 201 outputs information such as the spectrum 501 itself, the m/z corresponding to the peak of the spectrum 501, the signal intensity, and the presence or absence of the substance to be measured.

In the example shown in FIG. 1, the storage unit 220 is mounted on the data processing device 200, but this is not limiting. For example, the storage unit 220 may be installed as a device separate from the data processing device 200, such as a database.

[Hardware configuration]
FIG. 2 is a diagram illustrating an example of the hardware configuration of the data processing device 200. As shown in FIG.
The data processing device 200 includes a memory 231 including a RAM or the like, a calculation device 232 including a CPU, a GPU, or the like, and a storage device 233 including a HD, an SSD, or the like. The data processing device 200 also includes an input device 234 including a keyboard, a mouse, or the like, an output device 201, and a communication device 235.

If the data processing device 200 is equipped with a memory unit 220 (see FIG. 1), the storage device 233 corresponds to the memory unit 220. The output device 201 is the output device 201 shown in FIG. 1.

In addition, a program stored in the storage device 233 is loaded into the memory 231. The loaded program is then executed by the calculation device 232. This embodies the plot processing unit 211, the correction processing unit 212, and the measurement processing unit 213 shown in FIG. 1.

[Quadrupole mass filter 140]
3A and 3B are diagrams showing the configuration of the quadrupole mass filter 140. Fig. 3A shows a perspective view of the quadrupole mass filter 140, and Fig. 3B shows a cross section of the quadrupole mass filter 140 and a diagram showing voltage control for the quadrupole mass filter 140.
As shown in Figures 3A and 3B, the quadrupole mass filter 140 is composed of four quadrupole rod electrodes 141 (141a to 141d). As shown in Figure 3B, an RF voltage and a DC voltage are applied to each quadrupole rod electrode 141. The RF voltage is an AC voltage generated by an RF power supply 302 controlled by a voltage control device 300. The DC voltage is a DC voltage generated by a DC power supply 301 controlled by the voltage control device 300. In reality, a composite wave in which a DC voltage is applied to an RF voltage is applied to each of the quadrupole rod electrodes 141.

The composite wave of the RF voltage and DC voltage is applied so that it is in phase with each other between adjacent quadrupole rod electrodes 141 and in phase with each other between opposing quadrupole rod electrodes 141. In other words, in the example shown in FIG. 3B, RF voltages of opposite phases are applied between the pair of quadrupole rod electrodes 141a, 141c and the pair of quadrupole rod electrodes 141b, 141d.

As described above, the DC voltage is a direct current voltage generated by the DC power supply 301 controlled by the voltage control device 300. Here, if the DC voltage applied to the quadrupole rod electrodes 141a and 141c is VDC1, the DC voltage applied to the quadrupole rod electrodes 141b and 141d is -VDC1. The RF voltage and DC voltage applied to each quadrupole rod electrode 141 are appropriately referred to as the quadrupole RF voltage and the quadrupole DC voltage. The typical voltage amplitude of the quadrupole RF voltage is several hundreds of V to several kV, and the frequency is about 500 kHz to 2 MHz. The quadrupole DC voltage is about several tens of V to several hundreds of V.

(Operation of the quadrupole mass filter 140)
Next, the operation of the quadrupole mass filter 140 will be described with reference to FIG.
FIG. 4 is a diagram illustrating the operation of the quadrupole mass filter 140 and the relationship between the quadrupole RF voltage and the quadrupole DC voltage.
The m/z range of ions capable of stable orbital motion in the quadrupole mass filter 140 depends on the amplitude of the quadrupole RF voltage and the value of the quadrupole DC voltage. Only ions present inside the stability regions R1 to R3 shown in FIG. 4 can pass through the quadrupole mass filter 140. Here, the stability region R1 is the region within the line R1a, the stability region R2 is the region within the line R2a, and the stability region R3 is the region within the line R3a. The stability regions R1 to R3 are different for each m/z of the ions. The stability regions R1 to R3 are arranged in the relationship shown in FIG. 4 from ions with small m/z to ions with large m/z. That is, the stability region R1 is the stability region of ions having a certain m/z. Similarly, the stability region R2 is the stability region of ions with a different m/z from the ions in the stability region R1, and the stability region R3 is the stability region of ions with a different m/z from the ions in the stability regions R1 and R2.

If the quadrupole RF voltage and quadrupole DC voltage are set near the apex of the stability region R1-R3 of a certain m/z, it is possible to transmit only ions having that m/z. In addition, the quadrupole RF voltage is scanned so as to pass near the apex of the stability region R1-R3 of each m/z ion, as shown by the scan line L1 in Figure 4. In this case, by scanning the quadrupole RF voltage while maintaining the relationship between the quadrupole RF voltage and the quadrupole DC voltage, the spectrum 501 shown in Figure 5 can be obtained. In other words, it becomes possible to detect ions having each m/z.

(Calibration point correction process)
Next, the calibration point correction process will be described with reference to FIGS. 5 to 7B.
Fig. 5 is a graph showing the relationship between the quadrupole RF voltage and the ion signal intensity, and Fig. 6 is a graph showing the relationship between the m/z and the quadrupole RF voltage.
In Fig. 5, the horizontal axis indicates the quadrupole RF voltage, and the vertical axis indicates the ion signal intensity. Fig. 5 also shows a spectrum 501 of calibration ions. The calibration ions are ions generated from a calibration sample, and their m/z is known. Fig. 5 also shows a spectrum 502 of impurity ions. The impurity ions are ions derived from impurities due to contamination or the like.

In the following description, the quadrupole RF voltage refers to the amplitude value of the quadrupole RF voltage. The quadrupole RF voltage is the voltage obtained as a result of measuring multiple calibration ions with the mass spectrometer 100.

As shown in FIG. 5, spectrum 502 of impurity ions is detected in close proximity to spectrum 501a of calibration ions.

Also shown in FIG. 5 is a scan range 511, which is a voltage range. The scan range 511 is the scan width of the quadrupole RF voltage performed for ion detection. The scan range 511 will be described later.

Also, in the m/z-quadrupole RF voltage relationship graph shown in FIG. 6, calibration point 521 is plotted. As shown in FIG. 6, the m/z-quadrupole RF voltage relationship graph is a coordinate system having an m/z axis and a quadrupole RF voltage axis as coordinate axes. In other words, the m/z-quadrupole RF voltage relationship graph is a coordinate system having voltage and m/z as coordinate axes.

Calibration point 521 shows the relationship between the quadrupole RF voltage corresponding to the peak value of the ion signal intensity in spectrum 501 shown in FIG. 5 and m/z. As described above, the m/z of the calibration ions is known, so it is possible to plot an m/z-quadrupole RF voltage relationship graph as shown in FIG. 6. Calibration point 521 is a coordinate plot of the voltage obtained as a result of measuring multiple calibration ions with mass spectrometer 100 and the m/z of each calibration ion.

In FIG. 5, as described above, spectrum 502 due to impurity ions is detected near spectrum 501a due to calibration ions. Furthermore, the peak value of spectrum 501a is lower than the peak value of spectrum 502. Furthermore, in FIG. 5, spectrum 501a and spectrum 502 fall within the same scan range 511. This indicates that spectrum 501a and spectrum 502 are detected as one spectrum 501. This may cause the data processing device 200 to mistake the impurity ions for calibration ions and make a judgment.

As a result, as shown in FIG. 6, calibration point 521b derived from impurity ions is plotted close to calibration point 521a derived from spectrum 501a.

In this way, there may be impurity ions having adjacent m/z to the calibration ions. In such a case, as shown in spectra 501a and 502 in FIG. 5, the peak of spectrum 501a originating from the calibration ions and the peak of spectrum 502 originating from the impurity ions are close to each other. In this way, the data processing device 200 may confuse the peaks of the calibration ions and the impurity ions. When such a confusion occurs between the peaks of the calibration ions and the impurity ions, the value of the quadrupole RF voltage becomes different from the value of the quadrupole RF voltage of the actual calibration ions, as shown in FIG. 6. In other words, the m/z of the impurity ions is linked to the quadrupole RF voltage to which the m/z of the calibration ions that generate spectrum 501a should be linked. When measuring a substance with an unknown m/z, the m/z of the measured substance is output based on the m/z-quadrupole RF voltage relationship graph as shown in FIG. 6 and the obtained quadrupole RF voltage. However, if the m/z of the impurity ions is linked to the quadrupole RF voltage to which the m/z of the calibration ions that produce spectrum 501a should be linked, an incorrect m/z will be output.

The quadrupole DC voltage is determined so that the range of the spectrum 501 produced by the calibration ions is a specified (constant) value.

In addition, when acquiring spectrum 501, there is a time lag between when ions pass through the quadrupole mass filter 140 and when they are detected by the detector 152. This causes a phenomenon in which the value of the quadrupole RF voltage at the timing when the ions are detected by the detector 152 differs from the value of the quadrupole RF voltage at the timing when the ions pass through the quadrupole mass filter 140. As a result, the m/z of the ions detected changes depending on the scan speed.

During mass analysis, the quadrupole mass filter 140 operates to selectively transmit ions having a specific m/z while keeping the quadrupole RF voltage fixed for a certain period of time. To determine the quadrupole RF voltage that transmits ions having a specific m/z, the measurement processing unit 213 (see FIG. 1) rescans the quadrupole RF voltage in a specified range and obtains the peak value of the spectrum 501 shown in FIG. 5. Determining the quadrupole RF voltage corresponding to the m/z of the calibration ions based on this peak value is called voltage calibration. Note that the first scan is a scan in the presence of impurity ions as described below, and the rescan is a scan after correction of the calibration point 521 (see FIG. 6) described below has been performed.

In order to perform voltage calibration with high accuracy, it is desirable to perform mass analysis at a low scan rate. A low scan rate is, for example, about 0.1 Da/s to 100 Da/s (1.66×10 ⁻²⁵ g/s to 1.66×10 ⁻²² g/s). On the other hand, at a low scan rate, it takes a long time to acquire a spectrum 501 in a predetermined range. In other words, if the measurement processing unit 213 scans the entire quadrupole RF voltage range at a low scan rate, it will take an enormous amount of time. Therefore, there is a disadvantage in that the time required for voltage calibration is also long.

Therefore, a spectrum 501 is acquired by scanning only the vicinity of the calibration ions at a low scan speed, as shown in the scan range 511 shown by the dashed line in Figure 5. In this way, it is often possible to measure both the accuracy of the voltage calibration and the time required for the voltage calibration.

Next, the calibration point correction process in this embodiment will be described with reference to FIGS. 7A and 7B.
7A and 7B are graphs showing the relationship between m/z and quadrupole RF voltage, in which Fig. 7A shows an example in which no impurity ions are detected, and Fig. 7B shows an example in which peaks are confused due to impurity ions.
As shown in Fig. 7A, the m/z of the calibration ions stably passing through the quadrupole mass filter 140 is proportional to the (amplitude of) the quadrupole RF voltage. Therefore, when no impurity ions are detected, as shown in Fig. 7A, the slope (ai) of the line connecting the calibration points 521 (mi, xi) shown in formula (1) is approximately the same value for all the calibration points 521. Here, the slope (ai) is the slope between each of the calibration points 521.

ai = (xi+1 - xi)/(mi+1 - mi)...(1)

Here, mi (i = 1, ..., N) is the m/z value, xi (i1, ..., N) is the value of the quadrupole RF voltage, and i is the number of the calibration point 521.

In contrast, in FIG. 7B, at (mk, xk), the calibration ion (calibration point 521a) is confused with the adjacent impurity ion (calibration point 521b). As shown in FIG. 6 and FIG. 7B, the calibration point 521b of the impurity ion is plotted as an outlier. Incidentally, (mk, xk) indicates the coordinates of the calibration point 521 in the m/z-quadrupole RF voltage relationship graph. Due to the confusion between the calibration ion and the adjacent impurity ion, the correct calibration point 521a is recognized as the calibration point 521b of the impurity ion, and the corresponding quadrupole RF voltage is shifted. Therefore, the value of the slope (ak-1, ak) changes on both sides of mk, and as a result, the deviation (Di) of ai becomes large. The deviation (Di) is defined by the following formula (2). In this way, the deviation (Di) is the deviation with respect to each slope (ai).

Di = (ai - a_mean) ² ...(2)

Here, a_mean is the average of ai defined by the following formula (3). However, the deviation does not have to be the deviation from the average of ai. For example, the deviation (Di) may be defined as Di = ai - ai-1, etc.

 

 

As shown in FIG. 7A, if there is no confusion between impurity ions and calibration ions, the relationship between adjacent calibration points, that is, the value of the slope (ai) (i = 1, ..., N-1) between adjacent calibration points 521, will be approximately the same. Using this, in this embodiment, correction is performed for calibration points 521 whose peaks have been mistaken for impurity ions.

Specifically, in this embodiment, the correction processing unit 212 (see FIG. 1) determines whether a peak has been confused based on whether the standard deviation (SD) defined by the following formula (4) is equal to or greater than a threshold value (Sth). In other words, whether there is an outlier for each calibration point 521 is determined based on whether the standard deviation (SD) defined by the formula (4) is equal to or greater than a threshold value (Sth).

 

 

(flowchart)
8 is a flowchart showing the procedure of the mass spectrometry data processing method according to the first embodiment, with reference to FIGS.
First, the plot processing unit 211 performs a plotting process of plotting the measurement results of the calibration ions by the mass spectrometer 100 on an m/z-quadrupole RF voltage relationship graph (S101: first step). At this time, the plot processing unit 211 performs the plotting based on the quadrupole RF voltage obtained as a result of the scan in the scan range 511 shown in FIG. 5 and the m/z of the calibration ions that is known in advance.

Thereafter, the correction processing unit 212 calculates (S102) all of the slopes (ai) between the respective obtained calibration points 521. The slopes (ai) are calculated according to the formula (1).
Then, the correction processing unit 212 calculates the deviation (Di) for each of the inclinations (ai) (S103). The deviation (Di) is calculated according to the formula (2).
Next, the correction processing unit 212 calculates the standard deviation (SD) of the slope calculated in step S102 (S104). The standard deviation (SD) is calculated according to the formula (4).
Then, the correction processing unit 212 determines whether or not the standard deviation is greater than a preset standard deviation threshold value (Sth) (SD>Sth) (S105). In step S105, it is determined whether or not there is an outlier for each calibration point 521.
If the standard deviation is equal to or smaller than the threshold value of the standard deviation (S105→No), the data processing device 200 ends the process.

If the standard deviation is greater than the standard deviation threshold value (S105→Yes), the correction processing unit 212 sets the loop count (h) to "0" (h=0) (S111). If "Yes" is determined in step S105, this means that the correction processing unit 212 has determined that there is an outlier for each calibration point 521. In other words, the correction processing unit 212 determines that there is an outlier when the standard deviation (SD) of the deviation (Di) is greater than a preset threshold value.
Next, the correction processing unit 212 determines whether the number of loops (h) is greater than a preset maximum number of loops (hmax) (h>hmax) (S112).
If the loop count (h) is greater than the maximum loop count (hmax) (S112→Yes), the correction processing unit 212 outputs an error (S151).

If the number of loops (h) is equal to or less than the maximum number of loops (hmax) (S112→No), the correction processing unit 212 calculates the deviation (Di) for all between the calibration points 521 (S121). The correction processing unit 212 calculates the deviation (Di) according to formula (2).

Then, the correction processing unit 212 searches for the deviation (Dmax) having the largest value from among the deviations (Di) (S122).
Then, it is determined whether the maximum deviation (Dmax) is greater than a deviation threshold value (Dth) (S123).

If the deviation (Dmax) having the largest value is equal to or smaller than the deviation threshold value (Dth) (S123→No), the correction processing unit 212 advances the process to step S141.
If the deviation (Dmax) having the largest value is greater than the deviation threshold value (Dth) (S123→Yes), the calibration point is corrected (S124: second step). At this time, the correction processing unit 212 performs the correction by replacing the calibration point 521 corresponding to the deviation (Dmax) having the largest value. The detailed procedure of the correction will be described later. In step S124, the outlier of the calibration point 521 is corrected, and the calibration point 521 is corrected.

Then, the correction processing unit 212 uses the corrected calibration points 521 to recalculate all the slopes (ai) between the obtained calibration points 521 (S131).
Next, the correction processing unit 212 re-calculates the standard deviation (SD) of the inclination calculated in step S131 (S132). Note that, prior to step S132, the calculation of the deviation (Di) is performed in the same manner as in step S103A.
Then, the correction processing unit 212 judges whether or not the standard deviation (SD) calculated in step S132 is greater than a threshold value (Sth) of the standard deviation (SD>Sth) (S133). The threshold value (Sth) of the standard deviation used in step S133 is the same as that used in step S105.

If the standard deviation (SD) is greater than the standard deviation threshold value (Sth) (S133 → Yes), the correction processing unit 212 adds 1 (h++) to the loop count (h) (S134) and returns the process to step S112.

If the standard deviation (SD) is equal to or less than the standard deviation threshold value (Sth) (S133→Yes), the measurement processing unit 213 performs voltage calibration using the corrected calibration point 521 (S141). After that, the correction processing unit 212 returns the process to step S102. However, after step S141 is performed, the process does not necessarily have to return to step S102.

(Specific example)
Next, a specific example of the mass spectrometry data processing method shown in FIG. 8 will be described with reference to FIGS. 6 and 8 to 9B.
FIG. 9A is a diagram showing a table of specific values of the calibration points 521.
The table shown in FIG. 9A has items for the number of the calibration point 521, the reference m/z, and the quadrupole RF voltage. The reference m/z is the m/z of the calibration ion used. The quadrupole RF voltage item has items for the correct value, the measured value, and the corrected value. The correct value is the quadrupole RF voltage in the case where the calibration ion is not confused with the impurity ion. The corrected value is the quadrupole RF voltage after the above-mentioned calibration point correction is performed. If the acquired calibration point 521 is correct (if the peak is not confused), the correct value = the measured value = the corrected value.

The last row of the table in Figure 9A shows the standard deviation. The standard deviation is calculated for each of the correct value, the measured value, and the corrected value. Note that the standard deviation shown in Figure 9A is the standard deviation of the slope between the calibration points (ai shown in equation (1)).

In the example table shown in Figure 9A, the correct value differs from the actual measured value because the calibration point 251 number "6" has been confused with an impurity ion.

FIG. 9B is a diagram showing a graph of the deviation (Di) based on FIG. 9A.
In the graph shown in FIG. 9B, the horizontal axis represents the deviation number, and the vertical axis represents the magnitude of the deviation.
As shown in the example of Figure 9A, a mix-up has occurred at calibration point 521 (see Figure 6) number "6", resulting in a large deviation between deviation numbers "5" and "6" (i.e., the slope on both sides of calibration point 521 number "6").

Here, a specific procedure for correcting the calibration point when data of the calibration point 521 as shown in FIG. 9A is obtained will be described.
In this embodiment, the correction is performed by linearly correcting the calibration point 521 with a large deviation using the following formula (see FIG. 7B as appropriate).

First, when the correct quadrupole RF voltage value (x1) is calculated based on the first deviation (D1), the correct quadrupole RF voltage value (x1) is calculated using the following formula (11).

D1: x1=a2・m1+b2...(11)

Furthermore, when the correct quadrupole RF voltage value (xN) is calculated based on the Nth (last) deviation (DN), the correct quadrupole RF voltage value (xN) is calculated using the following formula (12).

DN: xN=aN-1・mN + bN-1...(12)

If the i-th (i = 2 to N-1) deviation Di is greater than the deviation threshold, the correct quadrupole RF voltage value (xi) is calculated using the following equations (13) and (14).

When Di+1>Di-1:
xi+1=ai+2・mi+1+bi+2...(13)
If Di+1≦Di−1:
xi=ai-1・mi+bi-1...(14)

In equations (11) to (14), xi and mi (i = 1, ..., N) are shown in Figures 7A and 7B, and ai (i = 1, ..., N) is calculated by equation (1). Furthermore, bi (i = 1, ..., N) is the intercept of the quadrupole RF voltage axis of a straight line that passes through the coordinates (mi, xi) on the m/z-quadrupole RF voltage relationship graph shown in Figures 7A and 7B and has a slope (ai). In this way, the correction processing unit 212 corrects the calibration point 512 based on the slope (ai).

Below, the processing performed in steps S122 to S141 in FIG. 8 will be described in detail with reference to FIGS. 7A, 7B, 9A, and 9B. Note that in the following description, the step numbers refer to the step numbers of the processing shown in FIG. 8.

As described above, the operation when a peak is confused at calibration point 521 (m/z: 1172.145) of number "6" in Fig. 9A will be described below as an example. At number "6" in Fig. 9A, the peak is confused with the peak of an impurity ion that is about 1.0 Da (1.66 x ^10-24 g) higher in unified atomic mass units.

(S122) The correction processing unit 212 searches for the deviation (Di) having the largest value from among all the deviations. Here, i is the deviation number shown in Fig. 9B. In the example shown in Fig. 9B, D5 (i = 5) = 0.186 indicated by reference numeral 601 is the largest.
(S123) The correction processing unit 212 determines whether or not the deviation value found in step S122 is equal to or greater than the deviation threshold value (Dth). It is assumed that D5 (reference numeral 601) shown in FIG. 9B is equal to or greater than the deviation threshold value.

(S124) The correction processing unit 212 corrects the calibration point 521 by replacing the calibration point 521 corresponding to the deviation (Dmax) having the largest value. Specifically, the quadrupole RF voltage (xi or xi+1) of the calibration point 521 (mi or mi+1) having the slope (ai) corresponding to the maximum deviation (Di) is replaced with a value corrected from the previous and next calibration points 521. The replacement is performed by the quadrupole RF voltage calculated according to equations (11) to (14).

In the example shown in FIG. 9B, D5 = 0.186 is the maximum deviation, and D6 > D4, so the correction processing unit 212 replaces the quadrupole RF voltage (xi+1) of the calibration point 521 numbered "6" with the value calculated by xi+1 = ai+2 mi+1 + bi+2 (equation (13)). As a result, as shown in FIG. 9A, the quadrupole RF voltage of the calibration point 521 numbered "6" is corrected to "111958".

(S131) The correction processing unit 212 recalculates the tilt (ai) using the quadrupole RF voltage corrected in step S124.
(S132) The correction processing unit 212 recalculates the standard deviation (SD) of the slope recalculated in step S131. In the case of the example shown in Fig. 9A, the standard deviation (SD) after correction is "0.099".

(S133) The correction processing unit 212 compares the corrected standard deviation with the standard deviation threshold value (Sth). In the example shown in FIG. 9A, the corrected standard deviation (SD) is "0.099" as described above, which is less than the standard deviation threshold value (Sth = 0.1714).

If the corrected standard deviation is equal to or less than the threshold value in step S133 (S133→No), the measurement processing unit 213 performs the process of step S141. In step S141, the measurement processing unit 213 performs voltage calibration for the corrected calibration point 521, using the corrected quadrupole RF voltage as the initial value (third step). Specifically, the measurement processing unit 213 performs the above-mentioned scan with the corrected quadrupole RF voltage as the initial value to reacquire the spectrum 501. Then, based on the reacquired spectrum 501, the measurement processing unit 213 estimates the quadrupole RF voltage corresponding to the peak value of the calibration ion shown in the spectrum 501a by correction. In this way, the correct quadrupole RF voltage can be acquired. The process performed in step S141 will be described later.

Also, in step S133, if the corrected standard deviation is greater than the threshold value (S133 → Yes), the correction processing unit 212 repeats the processes from step S112 onwards until the standard deviation becomes equal to or less than the threshold value. However, if the number of loops is greater than a predetermined number (hmax), the correction processing unit 212 outputs an error (S151).

9A, for calibration point 521 numbered "6", the quadrupole RF voltage after correction is "111958" (V) as described above. The difference between this quadrupole RF voltage and the correct quadrupole RF voltage "111977" (V) is only 19 (V) (=approximately 0.2 Da (0.332×10 ⁻²⁴ g)). As a result, in voltage calibration using the corrected quadrupole RF voltage as the initial value, it is possible to obtain a peak value derived from the correct calibration ions as described above. Furthermore, as shown by the dashed line and white circle in FIG. 9B, the deviation is also small.

In equation (1), which shows the slope between calibration points, the smaller the m/z difference (mi+1 - mi), the more sensitively it reflects the deviation in the amplitude of the quadrupole RF voltage. In many cases, a calibration sample is selected so that the calibration points 521 have uniform m/z spacing. However, there are cases where a calibration sample is selected in which the m/z spacing is not uniform. In this way, when the m/z spacing of the calibration points 521 is not uniform, the m/z difference (mi+1 - mi) between the calibration points may be weighted when calculating the standard deviation.

In addition, in this embodiment, after the calibration point 521 is corrected, voltage calibration (S141 in FIG. 8) is performed, but this is not limited to the above. After the calibration point 521 is corrected, only the correction result (i.e., the quadrupole RF voltage after correction) is stored in the memory unit 220, and the voltage calibration may be performed as a process separate from the correction of the calibration point 521.

(Voltage calibration)
10 is a diagram showing a voltage calibration method, with reference to FIG.
Fig. 10 is an enlarged view of spectrum 501a and the vicinity of spectrum 502 in the quadrupole RF voltage-ion signal intensity relationship graph shown in Fig. 5. The process shown in Fig. 10 is performed by the measurement processing unit 213 shown in Fig. 1 in step S141 in Fig. 8.
In the voltage calibration after the calibration point 521 is corrected by the correction, the measurement is started in a narrow scan range 511a centered on the quadrupole RF voltage (reference symbol 531) calculated by the corrected calibration point 521. That is, the scan range 511 is gradually widened from the narrow scan range 511 like the scan range 511a centered on the quadrupole RF voltage (reference symbol 531) estimated by the correction of the calibration point 521. Note that the number "6" in FIG. 9A shows that the difference between the quadrupole RF voltage by the correction of the calibration point 521 and the correct quadrupole RF voltage "111977" (V) is only 19 (V). In other words, the quadrupole RF voltage estimated by the correction of the calibration point 521 is not necessarily the true center of the spectrum 501a to be subjected to the voltage calibration. Therefore, in FIG. 10, the quadrupole RF voltage (reference symbol 531) calculated by the corrected calibration point 521 is shown at a position shifted from the center of the spectrum 501a.

The scan range 551 is changed each time a measurement is performed. In other words, the scan range 511 is gradually expanded from scan range 511a to scan range 511c. The scan range 511 is then gradually expanded until the calibration ion spectrum 501a enters scan range 511c. By starting the measurement from the narrow scan range 511 in this way, it is possible to prevent the spectrum 502a from being scanned. This makes it possible to prevent the peak of spectrum 501a from being confused with the peak of spectrum 502 due to adjacent impurity ions. It is also possible to obtain the true center of spectrum 501a.

In this way, in voltage calibration, the measurement processing unit 213 measures the calibration ions in the mass spectrometer 100 (see figure) in a scan range 511 centered on the quadrupole RF voltage calculated using the corrected calibration point 521. At this time, the measurement processing unit 213 changes the scan range 511 so that it becomes gradually wider each time a measurement is performed, as shown by scan ranges 511a to 511c in Figure 10.

Note that even though the quadrupole EF voltage corresponding to the peak value of spectrum 501a is estimated by calibration point 521, rescanning is performed as shown in FIG. 10. This is because, as described above, the quadrupole RF voltage value estimated by correction does not necessarily indicate the correct value, as shown by number "6" of calibration point 521 in FIG. 9A.

According to the first embodiment, when performing voltage calibration, even if there is an impurity ion having an m/z adjacent to the calibration point 521, it is possible to correct the peak confusion between the impurity ion and the calibration ion. This makes it possible to determine an accurate quadrupole RF voltage derived from the calibration ion. As a result, when performing mass analysis of an unknown substance, highly accurate mass analysis is possible. Furthermore, according to the first embodiment, correction of the calibration point 521 and voltage calibration can be performed even if there is only one peak confusion.

Second Embodiment
The second embodiment will be described below. Note that the configuration of the mass spectrometry system 1 in the second embodiment is similar to that shown in Fig. 1, and therefore illustration and description of the second embodiment will be omitted. In Fig. 12, the same components as those in Fig. 7B are given the same reference numerals, and description thereof will be omitted.

Hereinafter, the processing performed in the second embodiment will be described with reference to FIG. 11 and FIG.
Fig. 11 is a flow chart showing the procedure of the mass spectrometry data processing method according to the second embodiment. Fig. 12 is a graph showing the relationship between m/z and quadrupole RF voltage. In the following description, the step numbers are those shown in Fig. 11. In Fig. 11, the same step numbers are used for steps that are the same as those in Fig. 8, and descriptions thereof will be omitted as appropriate.
In the second embodiment, the correction processing unit 212 calculates the slope and intercept 711 by applying the least squares method to each of the calibration points 521. Then, the correction processing unit 212 compares the standard deviation and the threshold value based on the calculated slope. That is, in the first embodiment, in steps S102 and S131 of FIG. 8, the slope (ak) between the calibration points 521 is calculated one by one. In contrast, in the second embodiment, the correction processing unit 212 obtains a straight line 701 close to all the calibration points 521 as shown in FIG. 12 by the least squares method according to the following formula (21). That is, the correction processing unit 212 calculates the slope and intercept 711 of the straight line 701 by applying the least squares method to each of the calibration points 521 (S102A and S131A). That is, the straight line 701 has a slope and intercept 711 calculated by applying the least squares method to each of the calibration points 521. In this way, in the second embodiment, the slope between the respective calibration points 521 is unified to a slope obtained by the least squares method.

Then, the correction processing unit 212 calculates the deviation (Di) (S103A). In the second embodiment, the deviation (Di) is defined as the length of the perpendicular line 721 from each calibration point 521 to the straight line 701 obtained by the least squares method. The length of the perpendicular line 721 is the distance from the straight line 701 having the slope and intercept 711 for each calibration point 521. In this way, in step S103A, the correction processing unit 212 calculates the distance (length of the perpendicular line 721) from the straight line 701 having the slope and intercept 711 for each calibration point 512 as the deviation (Di).

Then, the correction processing unit 212 calculates the standard deviation (SD) of the deviation (Di) calculated in step S103A (S104A).

Then, if the standard deviation (SD) of the deviation (Di) is greater than a preset threshold (SD>Sth) (S105→Yes), the correction processing unit 212 corrects the calibration point 521 based on the slope. The procedure for correcting the calibration point 521 based on the slope is the same as in the first embodiment.

 

 

In equation (21), "slope" indicates the slope, and mi and xi indicate the m/z and quadrupole RF voltage as shown in Figures 7A and 7B. Furthermore, the variable with a bar above m indicates the average of mi. Furthermore, the variable with a bar above x indicates the average of xi (quadrupole RF voltage).

Then, the correction of the calibration point 521 is performed according to the following equation (22).

xi_cor=slope・mi+b...(22)

In equation (22), xi_cor indicates the value of the corrected quadrupole RF voltage, and b is the intercept 711 of the quadrupole RF voltage axis calculated by the least squares method. In other words, the corrected calibration point 521 is corrected to lie on the straight line 701 calculated by the least squares method.

In step S121A in FIG. 11, the deviation (Di) is calculated in the same manner as in step S103A. Although not shown in FIG. 11, before step S121A, the slope and intercept 711 are calculated in the same manner as in step S102A. Furthermore, step S131A is the same process as step S102A, and step S132A is the same process as step S104A. Furthermore, although not shown, between step S131A and step S132A, the same process as in step S103A is performed.

In this way, in the second embodiment, the misidentification of the peaks of impurity ions and calibration ions is corrected based on the slope calculated by using the least squares method for the calibration point 521.

In the method shown in the second embodiment, the slope between the calibration points 521 is calculated at once by the least squares method, compared to the first embodiment in which the slope between the calibration points 521 is calculated one by one. Therefore, the method shown in the second embodiment has simpler calculations and can be performed quickly compared to the method shown in the first embodiment.

Third Embodiment
Next, referring to FIG. 13, an example will be shown in which the calibration point correction process shown in the first and second embodiments is applied to a mass spectrometry system 1a in which a time-of-flight mass spectrometer 400 is installed in the analysis unit 103.
FIG. 13 is a diagram showing an example of the configuration of a mass spectrometry system 1a according to the third embodiment.
A mass spectrometer 100a in the mass spectrometer system 1a shown in FIG. 13 is similar to the mass spectrometer system 1 shown in FIG. 1 in the following respects.
(A1) The analysis section 103 is provided with a time-of-flight mass spectrometer 400 .
(A2) A power supply 410 that applies a pulse voltage is connected to a pushing electrode 401 that constitutes a time-of-flight mass spectrometer 400. This power supply 410 is controlled by a voltage control device 300.
In FIG. 13, the same components as those in FIG. 1 are denoted by the same reference numerals.

In the mass spectrometer 100a, ions generated in the ion source 151 are introduced into the first differential pumping section 101 through the aperture 121, as in FIG. 1. The first differential pumping section 101 is evacuated by the pump 111, as in FIG. 1. This allows the first differential pumping section 101 to be maintained at a vacuum level of 10 Pa to 500 Pa. The ions that have passed through the first differential pumping section 101 are introduced into the second differential pumping section 102 through the aperture 122. The second differential pumping section 102 is evacuated by the pump 112, as in FIG. 1. This allows the second differential pumping section 102 to be maintained at a vacuum level of 0.1 Pa to 10 Pa. Also, as in FIG. 1, the second differential pumping section 102 is provided with an ion guide 130 that focuses the ions. The ions focused by the ion guide 130 pass through the aperture 123 and are introduced into the analysis section 103 in which the time-of-flight mass spectrometer 400 is provided. As in FIG. 1, the analysis section 103 is evacuated by a pump 113. This keeps the analysis section 103 at a pressure of 1E-5 Pa or less.

The time-of-flight mass spectrometer 400 is composed of a pusher electrode 401, an acceleration electrode 402, a reflector electrode 403, and a detector 152. A pulse voltage is applied to the pusher electrode 401 by the power supply 410. By applying the pulse voltage, the pusher electrode 401 bends the traveling direction of some of the ions incident from the ion guide 130 to a direction perpendicular to the incident direction of the ions. The bent ions head toward the acceleration electrode 402. The ions whose traveling direction is bent are accelerated by the acceleration electrode 402 and reflected by the reflector electrode 403 (white arrow in Figure 13). The ions reflected by the reflector electrode 403 are detected by the detector 152. The time it takes for the ions bent by the pusher electrode 401 to reach the detector 152, that is, the flight time of the ions, depends on the m/z of the ions. Therefore, the spectrum 501 of the ions (see Figure 5) can be obtained by plotting the flight time and the signal intensity of the ions detected by the detector 152.

In the time-of-flight mass spectrometer 400, a multi-channel plate type detector 152 is generally used as the detector 152. The detection intensity of the ions is converted into an electrical signal (output signal) by the detector 152 and sent to the data processing device 200. At this time, similar to FIG. 1, the output signal output from the detector 152 is converted into digital data at a fixed sampling period and then sent to the data processing device 200. As in FIG. 1, the conversion to digital data is performed by an analog-to-digital converter (ADC) (not shown) or a pulse counting unit (not shown). The data processing device 200 stores the sent digital data in the memory unit 220.

In the mass spectrometry system 1a shown in FIG. 13, calibration ions can also be measured, and the techniques shown in the first and second embodiments can be applied to the obtained spectrum 501 (see FIG. 5). In this case, the amplitude of the pulse voltage applied to the pusher electrode 401 is used instead of the quadrupole RF voltage of the first embodiment. In other words, in the third embodiment, the pulse voltage is a voltage obtained as a result of measuring a plurality of calibration ions with the mass spectrometry device 100. Also, in the third embodiment, the quadrupole RF voltage axis of the m/z-quadrupole RF voltage relationship graphs shown in FIGS. 6 to 7B becomes the pulse voltage axis.

In the mass spectrometry system 1a, if there are impurity ions whose m/z is adjacent to the calibration point 521, the peak of the impurity ion may be confused with the peak of the calibration ion. However, by using a pulse voltage instead of the quadrupole RF voltage of the first embodiment, it is possible to perform processing similar to that of the first and second embodiments. This makes it possible to correct the confusion of the peaks. This makes it possible to obtain an accurate m/z when performing mass analysis on an unknown substance.

The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

Furthermore, the above-mentioned configurations, functions, plot processing unit 211, correction processing unit 212, measurement processing unit 213, storage unit 220, etc. may be realized in hardware by designing some or all of them as an integrated circuit, for example. Also, as shown in FIG. 2, the above-mentioned configurations, functions, etc. may be realized in software by a processor such as a CPU interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a memory, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, an SD (Secure Digital) card, or a DVD (Digital Versatile Disc), in addition to being stored in an HD (Hard Disk).

In addition, in each embodiment, the control lines and information lines shown are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are interconnected.

1, 1a Mass spectrometry system 100, 100a Mass spectrometer 140 Quadrupole mass filter 141, 141a to 141d Quadrupole rod electrode 152 Detector 200 Data processing device 211 Plot processing unit 212 Correction processing unit 213 Measurement processing unit 400 Time-of-flight mass spectrometer 501 Spectrum 501a Spectrum 502 Spectrum 511, 511a to 511c Scan range (voltage range)
521 Calibration point 521a Calibration point (calibration point by calibration ion)
521b Calibration point (outlier)
701 Straight line (including inclination)
711 Intercept 721 Perpendicular (Deviation)
S101 Plot process (first step)
S124 Correction (Second step)
S141 Mass calibration (third step)

Claims (10)

a plot processing unit that plots a voltage obtained as a result of measuring a plurality of calibration ions, each having a known m/z, by a mass spectrometer, and the m/z of each calibration ion as calibration points on a coordinate system having the voltage and the m/z as coordinate axes;
a correction processing unit that corrects the calibration points by correcting the outliers if there are outliers for the calibration points;
A data processing device having: 2. The data processing apparatus according to claim 1, further comprising a measurement processing unit that performs measurement of the calibration ions by the mass spectrometer within a voltage range centered on the voltage calculated based on the corrected calibration point. The measurement processing unit includes:
3. The data processing apparatus according to claim 2, wherein the voltage range is changed so that the voltage range becomes gradually wider each time the measurement is performed. The correction processing unit:
Calculating a slope between each of the calibration points;
Calculating the deviation for each of the slopes;
2 . The data processing device according to claim 1 , wherein, when the standard deviation of the deviations is greater than a preset threshold value, it is determined that the outlier exists, and the calibration point is corrected based on the slope. The correction processing unit:
Calculating a slope and an intercept by applying a least squares method to each of the calibration points;
2. The data processing device according to claim 1, further comprising: a calculation unit that calculates a deviation for each of the calibration points from a straight line having the slope and the intercept; and, if a standard deviation of the deviation is greater than a preset threshold, corrects the calibration points based on the slope. A mass spectrometer;
a plot processing unit that plots a voltage obtained as a result of measuring a plurality of calibration ions, each having a known m/z, by a mass spectrometer, and the m/z of each calibration ion as calibration points on a coordinate system having the voltage and the m/z as coordinate axes;
a correction processing unit that corrects the calibration points by correcting the outliers if there are outliers for the calibration points;
A mass spectrometry system comprising: 7. The mass spectrometry system according to claim 6, further comprising a measurement processing unit that performs measurement of the calibration ions by the mass spectrometer within a voltage range centered on the voltage calculated based on the corrected calibration point. The mass spectrometer is
7. The mass spectrometry system according to claim 6, wherein the analysis section comprises a quadrupole mass filter or a time-of-flight mass analyzer. A data processing device comprising:
a first step of plotting a voltage obtained as a result of measuring a plurality of calibration ions, each having a known m/z, by a mass spectrometer and the m/z of each calibration ion as calibration points on a coordinate system having the voltage and the m/z as coordinate axes;
a second step of correcting the calibration points by correcting any outliers associated with the calibration points;
A mass spectrometry data processing method for performing 10. The method for processing mass spectrometry data according to claim 9, further comprising: a third step of measuring the calibration ions by the mass spectrometer within a voltage range centered on the voltage calculated based on the corrected calibration point.

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