EP4737894A1

EP4737894A1 - Data processing device, mass spectrometry system, and mass spectrometry data processing method

Info

Publication number: EP4737894A1
Application number: EP24831860.2A
Authority: EP
Inventors: Masuyuki Sugiyama; Hideki Hasegawa; Tsugunao TOMA; Yuichiro Hashimoto
Original assignee: Hitachi High Tech Corp
Current assignee: Hitachi High Tech Corp
Priority date: 2023-06-30
Filing date: 2024-06-21
Publication date: 2026-05-06
Also published as: JPWO2025004999A1; CN120659994A; WO2025004999A1

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

FIELD OF THE INVENTION

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

BACKGROUND OF THE INVENTION

In a mass spectrometer, ions having a known m/z are measured, and the relationship between a specific parameter (a voltage applied to an electrode in a quadrupole mass filter) and the m/z is determined. In the measurement of a sample of unknown m/z, the m/z is determined by using such a technique.
Patent Document 1 describes that "the ionization unit 21 is controlled by the ionization control unit 1 so as to ionize an analysis sample and a mass calibration sample as analysis sample ions and mass calibration sample ions. An ion trap 23 is controlled by an ion dissociation control part 2 so as to capture an analysis sample ion and a mass calibration sample ion and selectively dissociate the mass calibration sample ion into a plurality of calibration fragment ions without selecting the analysis sample ion as a precursor ion. The mass analyzer 24 is controlled by the analysis control unit 3 so that the mass analysis of the analysis sample ions and the plurality of calibration fragment ions is performed. The mass-to-charge ratio of the analysis sample ion is calibrated by the calibration unit 4 based on the mass-to-charge ratios of the plurality of calibration fragment ions in the mass analysis spectrum obtained by the mass analysis. "(see Abstract).
Patent Document 2 discloses a method of measuring a mass spectrum under a plurality of conditions with different ionization polarities and the like, and performing mass axis calibration when there is a difference from reference data.

Prior Art Document

Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2019-86467
Patent Document 2: U.S. Patent Application Publication No. 2022 / 0246412

SUMMARY OF THE INVENTION

Problems to be solved by the invention

It is an object of the invention to determine an accurate mass axis even when an impurity ion whose m / z is adjacent to a calibration point exists when performing mass axis calibration.
In the technique described in Patent Document 1, since sample ions and impurity ions coexist, when the m / z of the fragment ions for calibration and the m / z of the impurity ions are adjacent to each other, there is a case where an accurate mass axis cannot be determined due to a mistake of peaks.
In the technique described in Patent Document 2, when the m / z of the calibration sample ion and the m / z of the impurity ion are adjacent to each other, it is not possible to determine which of the peaks of the adjacent spectra is the calibration sample ion. Therefore, in the technique described in Patent Document 2, even if an abnormality can be detected from a difference from the reference data, it is not possible to obtain confirmation that the ion is a calibration sample ion.
The present invention has been made in view of such a background, and an object of the present invention is to enable mass spectrometry with high accuracy.

Means to solve the problem

In order to solve the above-described problem, the present invention includes a plot processing unit that plots voltages acquired as a result of measuring a plurality of calibration ions having known m / z values by a mass spectrometer and the m / z values of the respective calibration ions as calibration points on coordinates having the voltages and the m / z values as coordinate axes, and a correction processing unit that corrects the calibration points by correcting outliers when there are outliers for the respective calibration points. Other solutions will be described in the embodiments as appropriate.

Advantage of the Invention

According to the present invention, mass spectrometry with high accuracy can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS

[Fig. 1] Fig. 1 is a diagram showing a configuration example of a mass spectrometry system according to a first embodiment.
[Fig. 2] Fig. 2 is a diagram illustrating an example of a hardware configuration of a data processing device;
[Fig. 3A] Fig. 3A is a diagram (part 1) showing a configuration of a quadrupole mass filter.
[Fig. 3B] Fig. 3B is a diagram (part 2) showing the configuration of a quadrupole mass filter.
[Fig. 4] Fig. 4 shows the operation of a quadrupole mass filter as a function of the quadrupole RF and DC voltages.
[Fig. 5] Fig. 5 is a graph showing the relationship between the quadrupole RF voltage and the ion signal intensity.
[Fig. 6] Fig. 6 is a graph (part 1) showing the relationship between m/z and quadrupole RF voltage.
[Fig. 7A] Fig. 7A is a diagram (part 2) showing a graph of m/z-quadrupole RF voltage relation.
[Fig. 7B] Fig. 7B is a diagram (part 3) showing a graph of m/z-quadrupole RF voltage relation.
[Fig. 8] Fig. 8 is a flowchart showing a procedure of a mass spectrometry data processing method according to the first embodiment.
[Fig. 9A] Fig. 7A is a diagram showing a table of specific values of calibration points.
[Fig. 9B] Fig. 7B is a graph of deviation.
[Fig. 10] Fig. 10 is a diagram showing a voltage calibration method.
[Fig. 11] Fig. 11 is a flowchart showing a procedure of a mass spectrometry data processing method according to a second embodiment.
[Fig. 12] Fig. 12 is a graph (part 4) showing the relationship between m/z and quadrupole RF voltage.
[Fig. 13] Fig. 13 is a diagram showing a configuration example of a mass spectrometry system according to a third embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, modes for carrying out the present invention (referred to as "embodiments") will be described in detail with reference to the drawings as appropriate.

First Embodiment

[Mass Spectrometry System 1]

Fig. 1 is a diagram illustrating a configuration example of a mass spectrometry system 1 according to a first embodiment. The mass spectrometry system 1 includes a mass spectrometer 100, a voltage control device 300, a DC power supply 301,303, 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. In Fig. 1, the broken lines connecting the voltage control device 300 with the DC power supply 301,303, the RF power supply 302, and the data processing device 200 and the broken lines connecting the detector 152 with the data processing device 200 represent signal lines. The solid line connecting the DC power supply 303 and the ion guide 130 and the solid line 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 region 101, a second differential pumping region 102, and an analysis region 103. Ions generated by the ion source 151 are introduced into the first differential pumping region 101 through the aperture 121. The ion source 151 is configured by an electrospray ion source, an atmospheric pressure chemical ion source, an atmospheric pressure photo-ion source, an atmospheric pressure matrix-assisted laser desorption ion source, or the like, and operates at atmospheric pressure or a vacuum lower than atmospheric pressure.
The first differential pumping region 101 is evacuated by a pump 111. Accordingly, the first differentially pumping region 101 is maintained at a vacuum level from 10Pa to 500Pa. The ions that have passed through the first differential pumping region 101 are introduced into the second differential pumping region 102 through the aperture 122. The second differential pumping region 102 is evacuated by the pump 112. Accordingly, the second differentially pumping region 102 is maintained at a vacuum level of 0. 1Pa to 10Pa. The second differential pumping region 102 is provided with an ion guide 130 for converging ions. The ions converged by the ion guide 130 are introduced into the analysis unit 103 in which the quadrupole mass filter 140 is installed via the aperture 123.
A static voltage (hereinafter referred to as a DC voltage) is applied to the ion guide 130 from a DC power supply 303. The RF power supply 302 applies a composite wave of a high frequency voltage (hereinafter referred to as an RF voltage) generated by the RF power supply 302 and a DC voltage sent from the DC power supply 301 to the quadrupole mass filter 140.
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, the RF voltage is supplied from the RF power source 302 controlled by the voltage control device 300 to the quadrupole rod electrodes 141 (see Figs. 3A and 3B) of the quadrupole mass filter 140. The high frequency component of the RF voltage is supplied from the quadrupole rod electrode 141 to the ion guide rod electrode of the ion guide 130 through the dielectric 153. With such a configuration, the number of power supplies can be reduced as compared with a configuration in which an RF voltage is individually supplied to the ion guide 130 and the quadrupole mass filter 140, and the mass spectrometry system 1 can be made inexpensive.
The analysis unit 103 is evacuated by the pump 113. Thus, the pressure in the analyzing section 103 is maintained at a pressure equal to or lower than 1E minus 3Pa. In the quadrupole mass filter 140, ions are separated according to m / z.
The ions that have passed through the quadrupole mass filter 140 are detected by the detector 152. As the detector 152, an electron multiplier, a type of a combination of a scintillator and a photomultiplier tube, or a multi-channel plate can be generally 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 of a certain sampling period (typically, 1 µ s to 1000 µ s), and then sent to the data processing device 200. The conversion into digital data is performed by an analog-digital converter (ADC) (not shown) or a pulse counting unit (not shown). The data processing device 200 stores the transmitted digital data in the storage 220.
In the data processing device 200, a plot processing unit 211, a correction processing unit 212, and a measurement processing unit 213 are implemented in addition to the storage 220. The plot processing unit 211 plots a calibration point 521 (Figs. 6 to 7B) on the m / z-quadrupole RF voltage relation graph shown in Figs. 6 to 7B. The correction processing unit 212 corrects the calibration point 521 based on the calibration point 521 plotted by the plot processing unit 211. The measurement processing unit 213 controls measurement by the mass spectrometer 100.
The storage 220 is formed of a memory, an HD, or the like, and can store and hold information such as numerical values and relational expressions necessary for performing correction in addition to data of the spectrum 501 (see Fig. 5). The plot processing unit 211, the correction processing unit 212, and the measurement processing unit 213 each include a temporary memory for temporarily storing a numerical value necessary for a calculation function or calculation. Further, the data processing device 200 has a function of controlling the voltage control device 300 or the like that controls each electrode or the like, and a function of outputting information to the output device 201, in addition to the function of accumulating and converting the information. The output device 201 is configured by a display, a printer, or the like. The output device 201 outputs information such as the spectrum 501 itself, m / z corresponding to the peak of the spectrum 501, signal intensity, and the presence or absence of a substance to be measured.
In the example illustrated in Fig. 1, the storage 220 is mounted on the data processing device 200, but the present invention is not limited thereto. For example, the storage 220 may be installed as a device such as a database different from the data processing device 200.

[Hardware Configuration]

Fig. 2 is a diagram illustrating an example of a hardware configuration of the Data processing device 200. The Data processing device 200 includes a memory 231 configured by a RAM or the like, an arithmetic device 232 configured by a CPU, a GPU, or the like, and a storage device 233 configured by an HD, an SSD, or the like. The data processing device 200 also includes an input device 234 including a keyboard, a mouse, and the like, an output device 201, and a communication device 235.
In a case where the storage 220 (see Fig. 1) is mounted on the data processing device 200, the storage device 233 corresponds to the storage 220. The output device 201 is the output device 201 illustrated in Fig. 1.
In addition, the program stored in the storage device 233 is loaded into the memory 231. Then, the loaded program is executed by the arithmetic device 232. This realizes the plot processing unit 211, the correction processing unit 212, and the measurement processing unit 213 illustrated in Fig. 1.

[Quadrupole Mass Filter 140]

Figs. 3A and 3B are diagrams showing the configuration of the quadrupole mass filter 140. A perspective view of the quadrupole mass filter 140 is shown in Fig. 3A, and a cross-sectional view of the quadrupole mass filter 140 and a view showing voltage control for the quadrupole mass filter 140 are shown in Fig. 3B. As shown in Figs. 3A and 3B, the quadrupole mass filter 140 is constituted by four quadrupole rod electrodes 141 (141a to 141d). As shown in Fig. 3B, an RF voltage and a DC voltage are applied to the respective quadrupole rod electrodes 141. The RF voltage is an alternating voltage generated by an RF power supply 302 controlled by a voltage control device 300. The DC voltage is a DC voltage generated by the DC power supply 301 controlled by the voltage control device 300. In practice, a composite wave of an RF voltage and a DC voltage is applied to each of the quadrupole rod electrodes 141.
The composite wave of the RF voltage and the DC voltage is applied so as to be in opposite phase between the adjacent quadrupole rod electrodes 141 and to be in phase between the facing quadrupole rod electrodes 141. That is, in the example shown in Fig. 3B, RF voltages of opposite phases are applied between the pair of quadrupole rod electrodes 141a and 141c and the pair of quadrupole rod electrodes 141b and 141d.
As described above, the DC voltage is a DC voltage generated by the DC power supply 301 controlled by the voltage control device 300. Here, when 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 the DC voltage applied to the respective quadrupole rod electrodes 141 are appropriately referred to as a quadrupole RF voltage and a quadrupole DC voltage. The typical voltage amplitudes of the quadrupole RF voltages are from a few 100V to a few kV, and the frequencies are on the order of 500kHz to 2MHz. The quadrupole DC voltage is on the order of a few 10V to a few 100V.

(Operation of Quadrupole Mass Filter 140)

The operation of the quadrupole mass filter 140 will now be described with reference to Fig. 4. Fig. 4 is a diagram showing 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 that can undergo 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 that are inside the stability region R1 to R3 shown in Fig. 4 can pass through the quadrupole mass filter 140. Here, the stable region R1 is a region within the line R1a, the stable region R2 is a region within the line R2a, and the stable region R3 is a region within the line R3a. The stable regions R1 to R3 are different for each m/z of the ions. The stable regions R1 to R3 are arranged in the relationship shown in Fig. 4 from an ion having a small m / z to an ion having a large m / z. That is, the stable region R1 is a stable region of ions having a certain m / z. Similarly, the stable region R2 is a stable region of ions having m / z different from that of the ions in the stable region R1, and the stable region R3 is a stable region of ions having m / z different from that of the ions in the stable regions R1 and R2.
If the quadrupole RF voltage and the quadrupole DC voltage are set in the vicinity of the apex of the stable region R1 to R3 of a certain m/z, only the ions having the m/z can be transmitted. Further, the quadrupole RF voltage is scanned so as to pass through the vicinity of the apex of the stable regions L1 to R3 of the ions of each m / z as in the scan line R1 shown in Fig. 4. At this time, the quadrupole RF voltage is scanned while maintaining the relationship between the quadrupole RF voltage and the quadrupole DC voltage, whereby the spectrum 501 shown in Fig. 5 can be obtained. That is, ions having each m/z can be detected.

(Calibration Point Correction Processing)

Next, the calibration point correction process will be described with reference to Figs. 5 to 7B. Fig. 5 is a graph showing a relationship between a quadrupole RF voltage and an ion signal intensity, which indicates a relationship between a quadrupole RF voltage and an ion signal intensity. Fig. 6 is a graph showing the relationship between m/z and quadrupole RF voltage. In Fig. 5, the horizontal axis represents the quadrupole RF voltage, and the vertical axis represents the ion signal intensity. In Fig. 5, a spectrum 501 by the calibration ions is shown. The calibration ions are ions generated from a calibration sample, and the m / z thereof is known. In Fig. 5, a spectrum 502 due to the impurity ions is detected. The impurity ions are ions derived from impurities due to contamination or the like.
In the following description, the quadrupole RF voltage indicates the amplitude value of the quadrupole RF voltage. The quadrupole RF voltage is a voltage acquired as a result of measuring a plurality of calibration ions by the mass spectrometer 100.
As shown in Fig. 5, the spectrum 502 of the impurity ions is detected in a state of being close to the spectrum 501a of the calibration ions.
In addition, a scan range 511, which is a voltage range, is illustrated in Fig. 5. The scan range 511 is a scan width of the quadrupole RF voltage performed for ion detection. The scan range 511 will be described later.
In addition, in the m/z-quadrupole RF voltage relationship graph shown in Fig. 6, a calibration point 521 is plotted. As shown in Fig. 6, the m/z-quadrupole RF voltage relationship graph is a coordinate having an m/z axis and a quadrupole RF voltage axis as coordinate axes. That is, the m/z-quadrupole RF voltage relationship graph is a coordinate having each of the voltage and m/z as a coordinate axis.
A calibration point 521 indicates a relationship between the quadrupole RF voltage corresponding to the peak value of the ion signal intensity in the spectrum 501 illustrated in Fig. 5 and m / z. As described above, since the m / z of the calibration ion is known, it is possible to draw a graph of the relationship between m / z and the quadrupole RF voltage as shown in Fig. 6. The calibration point 521 is a point where the voltage acquired as a result of measuring a plurality of calibration ions by the mass spectrometer 100 and the m / z of each calibration ion are plotted on the coordinates.
In Fig. 5, as described above, the spectrum 502 of the impurity ions is detected in the vicinity of the spectrum 501a of the calibration ions. The peak of the spectrum 501a is lower than the peak of the spectrum 502. In Fig. 5, the spectrum 501a and the spectrum 502 are included in the same scan range 511. This indicates that the spectrum 501a and the spectrum 502 are detected as one spectrum 501. This may cause the data processing device 200 to determine the impurity ions as calibration ions.
Therefore, as shown in Fig. 6, the calibration point 521b derived from the impurity ions is plotted in the vicinity of the calibration point 521a derived from the spectrum 501a.
As described above, there is a case where there is a contaminant ion having an adjacent m / z to the calibration ion. In such a case, as shown in the spectrum 501a 502 in Fig. 5, the peak of the spectrum 501a derived from the calibration ion and the peak of the spectrum 502 derived from the impurity ion are close to each other. In this manner, the data processing device 200 may mistake the peaks of the calibration ions and the impurity ions. When the peaks of the calibration ions and the impurity ions are mistaken for each other, the value of the quadrupole RF voltage becomes different from the value of the actual quadrupole RF voltage of the calibration ions as shown in Fig. 6. That is, the m / z of the impurity ions is coupled to the quadrupole RF voltage to which the m / z of the calibration ions that cause the spectrum 501a should be coupled. When a substance whose m/z is unknown is measured, 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 coupled to the quadrupole RF voltage to which the m / z of the calibration ions causing the spectrum 501a should be coupled, an erroneous m / z is output.
The quadrupole DC voltage is determined so that the range of the spectrum 501 by the calibration ions becomes a predetermined (constant) value.
In addition, when the spectrum 501 is acquired, there is a time lag from when the ions pass through the quadrupole mass filter 140 to when the ions are detected by the detector 152. Therefore, a phenomenon occurs in which the value of the quadrupole RF voltage at the timing when the ions are detected by the detector 152 is different from the value of the quadrupole RF voltage at the timing when the ions pass through the quadrupole mass filter 140. Therefore, the m / z of the detected ions changes depending on the scan speed.
During mass analysis, the quadrupole mass filter 140 performs an operation of selectively transmitting ions having a specific m / z in a state where the quadrupole RF voltage is fixed for a certain period of time. In order to determine the quadrupole RF voltage that transmits ions having a specific m/z, the measurement processing unit 213 (see Fig. 1) re-scans the quadrupole RF voltage in a predetermined range and acquires the peak value of the spectrum 501 shown in Fig. 5. Determining the quadrupole RF voltage corresponding to the m / z of the calibration ion based on the peak value is referred to as voltage calibration. The first scan is a scan in a state where impurity ions are present as described later, and the rescan is a scan after correction of a calibration point 521 (see Fig. 6) described later is performed.
In order to perform voltage calibration with high accuracy, it is desirable to perform mass spectrometry at a low scan speed. The low scan speed is, for example, about 0. 1Da / s to 100Da / s (1.66 × 10 - 25g / s to 1.66 × 10 - 22g / s). On the other hand, at a low scan speed, the time for acquiring the spectrum 501 in the predetermined range becomes long. That is, if the measurement processing unit 213 scans the entire range of the quadrupole RF voltage at a low scan speed, a huge amount of time is required. Therefore, there is a disadvantage that the time required for voltage calibration is also long.
Therefore, only the vicinity of the calibration ions is scanned at a low scan speed to acquire a spectrum 501 as in a scan range 511 indicated by a dashed-dotted line in Fig. 5. In this way, both the accuracy of the voltage calibration and the time required for the voltage calibration are often achieved.
Next, the calibration point correction process in the present embodiment will be described with reference to Figs. 7A and 7B. Figs. 7A and 7B are graphs showing the relationship between m/z and quadrupole RF voltage. Fig. 7A shows an example in which no impurity ion is detected, and Fig. 7B shows an example in which a peak is misidentified due to an impurity ion. As shown in Fig. 7A, the m / z of the calibration ions that stably pass through the quadrupole mass filter 140 is proportional to the quadrupole RF voltage (the magnitude thereof). Therefore, when no impurity ion is detected, the slope (ai) of the straight line connecting the calibration points 521 (mi, xi) expressed by the equation (1) has substantially the same value among all the calibration points 521, as shown in Fig. 7A. Here, the slope (ai) is a slope between the calibration points 521. $Ai = (xi + 1 - xi) / (mi + 1 - mi)$
Here, mi (i = 1,..., N) is the value of m / z, and xi (i1,..., N) is the value of the quadrupole RF voltage. Further, i is the number of the calibration point 521.
On the other hand, in Fig. 7B, a mix-up occurs between the calibration ion (calibration point 521a) and the adjacent impurity ion (calibration point 521b) at (mk, xk). As shown in Fig. 6 and Fig. 7B, the calibration points 521b of the impurity ions are plotted as outliers. Incidentally, (mk, xk) indicates the coordinates of the calibration point 521 in the m / z-quadrupole RF voltage relationship graph. Due to the mistaking of 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 increases. The deviation (Di) is defined by the following equation (2). Thus, the deviation (Di) is a deviation with respect to the respective slope (ai). $Di = {(ai - a_mean)}^{2}$
Here, a_mean is the mean of ai defined by the following Equation (3). However, the deviation does not have to be a deviation with respect to the average of ai. For example, the deviation (Di) may be defined as Di = ai-ai-1.
[Number 1] $a_{mean} = \frac{1}{N - 1} \sum_{1}^{N - 1} a_{i}$
As shown in Fig. 7A, when there is no misidentification of the impurity ion and the calibration ion, the relationship between the adjacent calibration points, that is, the value of the slope (ai) (I = 1,., N-1) between the adjacent calibration points 521 is substantially the same value. By using this, in the present embodiment, the calibration point 521 at which the peak is mistaken for the impurity ion is corrected.
Specifically, in the present embodiment, the correction processing unit 212 (see Fig. 1) determines whether or not the mix-up of the peaks occurs depending on whether or not a standard deviation (SD) defined by the following Expression (4) is equal to or greater than a threshold value (Sth). In other words, whether or not there is an outlier for each calibration point 521 is determined depending on whether or not the standard deviation (SD) defined by Equation (4) is equal to or greater than the threshold value (Sth).
[Number 2] $S = \sqrt{\frac{\sum_{1}^{N - 1} D_{i}}{N - 1}}$

(Flowchart)

Fig. 8 is a flowchart showing a procedure of a mass spectrometry data processing method according to the first embodiment. Reference is made to Figs. 1 and 6, and the like as appropriate. First, the plot processing unit 211 performs plot processing of plotting the results of measuring the calibration ions by the mass spectrometer 100 on the m / z-quadrupole RF voltage relation graph (S101: first step). At this time, the plot processing unit 211 performs plotting based on the quadrupole RF voltage obtained as a result of scanning in the scan range 511 shown in Fig. 5 and the m / z of the calibration ion known in advance.
Thereafter, the correction processing unit 212 calculates all the inclinations (ai) between the obtained calibration points 521 (S102). The slope (ai) is calculated according to Equation (1). Then, the correction processing unit 212 calculates a deviation (Di) related to each inclination (ai) (S103). The deviation (Di) is calculated according to Equation (2). Subsequently, the correction processing unit 212 calculates standard deviations (SD) of the inclinations calculated in step S102 (S104). The standard deviation (SD) is calculated according to equation (4). Then, the correction processing unit 212 determines whether the standard deviations are larger than a threshold (Sth) of the standard deviations set in advance (SD> Sth) (S105). It is determined whether there are outliers for each calibration point 521 in Step S105. If the standard deviations are equal to or smaller than the threshold of the standard deviations (S105 → No), the data-processing device 200 ends the processing.
When the standard deviations are larger than the threshold of the standard deviations (S105 → Yes), the correction processing unit 212 sets the number of loops (h) to "0" (h = 0) (S111). The determination of "Yes" in step S105 means that the correction processing unit 212 determines that there is an outlier for each calibration point 521. That is, the correction processing unit 212 determines that there is an outlier when the standard deviation (SD) of the deviation (Di) is larger than a preset threshold value. Subsequently, the correction processing unit 212 determines whether or not the loop count (h) is larger than a maximum loop count (hmax) set in advance (h> hmax) (S112). When the loop count (h) is larger than the maximum loop count (hmax) (S112 → Yes), the correction processing unit 212 outputs an error (S151).
When the loop count (h) is equal to or less than the maximum loop count (hmax) (S112 → No), the correction processing unit 212 calculates the deviation (Di) for all the calibration points 521 (S121). The correction processing unit 212 calculates the deviation (Di) according to Equation (2).
Then, the correction processing unit 212 searches for the largest deviation (Dmax) from the deviations (Di) (S122). Then, it is determined whether the largest deviation (Dmax) is larger than a deviation threshold (Dth) (S123).
When the largest deviation (Dmax) is equal to or smaller than the deviation threshold (Dth) (S123 → No), the correction processing unit 212 advances the process to step S141. If the largest deviation (Dmax) is larger than the deviation threshold (Dth) (S123 → Yes), the calibration point is corrected (S124: second step). At this time, the correction processing unit 212 performs 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. Thus, the outliers of the calibration points 521 is corrected, and the calibration points 521 is corrected in step S124.
Then, the correction processing unit 212 calculates all the obtained inclinations (ai) between the calibration points 521 again using the corrected calibration points 521 (S131). Subsequently, the correction processing unit 212 calculates the standard deviations (SD) of the inclinations calculated in step S131 again (S132). In the preceding stage of step S132, the deviation (Di) is calculated in the same manner as in step S103A. Then, the correction processing unit 212 determines whether or not the standard deviations (SD) calculated in step S132 are larger than the threshold values (Sth) of the standard deviations (SD> Sth) (S133). The threshold of standard deviations (Sth) used in step S133 is the same as that used in step S105.
When the standard deviations (SD) are larger than the threshold (Sth) of the standard deviations (S133 → Yes), the correction processing unit 212 adds 1 to the loop count (h) (h + +) (S134), and returns the processing to step S112.
When the standard deviations (SD) are equal to or less than the threshold (Sth) of the standard deviations (S133 → Yes), the measuring processor 213 performs the voltage calibration using the corrected calibration point 521 (S141). Thereafter, the correction processing unit 212 returns the process to step S102. However, after the step S141 is performed, the process does not necessarily have to return to the step S102.

(Specific Example)

Next, a concrete 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 table of specific values of the calibration point 521. The table shown in Fig. 9A has items of the number of the calibration point 521, m / z for reference, and quadrupole RF voltage. The m/z for reference is the m/z of the calibration ion used. The item of the quadrupole RF voltage includes items of a correct value, an actual measurement value, and a corrected value. The correct value is the quadrupole RF voltage in the case where the calibration ion and the impurity ion are not mistaken for each other. The corrected value is the quadrupole RF voltage after the calibration point correction is performed. If the acquired calibration point 521 is correct (if there is no mistaking of peaks), the correct value = the actual measurement value = the value after correction.
The last row of the table shown in Fig. 9A shows standard deviations. The standard deviation is calculated for each of the correct value, the actual measurement value, and the corrected value. The standard deviations shown in Fig. 9A are standard deviations of the slopes (ai shown in Equation (1)) between the calibration points.
In the example of the table shown in Fig. 9A, since the number "6" of the calibration point 251 is mistaken for the impurity ion, the correct value and the actual measurement value are different.
Fig. 9B is a graph of the deviation (Di) based on Fig. 9A. In the graph shown in Fig. 9B, the horizontal axis represents the number of the deviation, and the vertical axis represents the magnitude of the deviation. As shown in the example of Fig. 9A, since the mix-up occurs at the number "6" of the calibration point 521 (see Fig. 6), the deviation between the numbers "5" and "6" of the deviation (that is, the inclinations on both sides of the calibration point 521 of the number "6") is large.
Here, a specific procedure of the calibration point correction in the case where the calibration point 521 as shown in Fig. 9A is obtained will be described. The correction in the present embodiment is performed by linearly correcting the calibration point 521 having a large deviation using the following equation (see Fig. 7B as appropriate).
First, when the correct value (x1) of the quadrupole RF voltage is calculated based on the first (initial) deviation (D1), the correct value (x1) of the quadrupole RF voltage is calculated by the following Equation (11). $D 1 : x 1 = a 2 \cdot m 1 + b 2$
Further, when the correct value (xN) of the quadrupole RF voltage is calculated based on the Nth (last) deviation (DN), the correct value (xN) of the quadrupole RF voltage is calculated by the following Equation (12). $DN : xN = aN - 1 \cdot mN + bN - 1$
When the i-th (i = 2 to N-1) deviation Di is larger than the threshold value of the deviation, the correct value (xi) of the quadrupole RF voltage is calculated by the following equations (13) and (14). $\begin{array}{l} If Di + 1 > Di - 1 : \\ Xi + 1 = ai + 2 \cdot mi + 1 + bi + 2 \end{array}$ $\begin{array}{l} If Di + 1 \leq Di - 1 : \\ Xi = ai - 1 \cdot mi + bi - 1 \end{array}$
In Equations (11) to (14), xi and mi (i = 1,..., N) are shown in the Figs. 7A and Fig. 7B, and ai (i = 1,..., N) is calculated by Equation (1). Further, bi (i =1,..., N) is an intercept of the quadrupole RF voltage axes on a straight line passing through the coordinates (mi, xi) on the m / z-quadrupole RF voltage relational graphs shown in Figs. 7A and Fig. 7B and having a slope (ai). In this manner, the correction processing unit 212 corrects the calibration point 512 based on the inclination (ai).
Hereinafter, 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. In the following description, the step numbers are the step numbers of the processing shown in Fig. 8.
As described above, the operation in the case where the misidentification of the peak occurs at the calibration point 521 (m / z: 1172.145) of the number "6" in Fig. 9A will be described below as an example. In the number "6" in Fig. 9A, there is a misidentification with the high impurity ion peak which is about 1. 0Da (1.66 × 10 - 24g) higher in the unified atomic mass unit.
(S122) The correction unit 212 searches for the largest deviation (Di) among all the deviations. Here, i is the number of the deviation shown in Fig. 9B. In the example shown in Fig. 9B, D5 (i = 5) = 0.186 indicated by reference numeral 601 is the maximum.
(S123) The correction processing unit 212 determines whether or not the deviation found in step S122 is equal to or greater than the deviation threshold (Dth). D5 (reference numeral 601) shown in Fig. 9B is assumed to be equal to or greater than the threshold of the deviation.
(S124) The correction unit 212 corrects the calibration point 521 by replacing the calibration point 521 corresponding to the largest deviation (Dmax). Specifically, the quadrupole RF voltage (xi or xi + 1) of the calibration point 521 (mi or mi + 1) of the slope (ai) corresponding to the maximum deviation (Di) is replaced with a value corrected from the calibration points 521 before and after the calibration point. The permutation is performed by the quadrupole RF voltages calculated according to equations (11) - (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 of number "6" with a value obtained 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 having the number "6" is corrected to "111958".
(S131) The correction processing unit 212 recalculates the gradient (ai) using the corrected quadrupole RF voltage at step S124.
(S132) The correction processing unit 212 recalculates the standard deviations (SD) of the inclinations recalculated in step S131. In the example shown in Fig. 9A, the corrected standard deviations (SD) are "0.099".
(S133) The correction processing unit 212 compares the corrected with the threshold (Sth) of the standard deviation. In the example shown in Fig. 9A, the corrected standard deviations (SD) are "0.099", which is equal to or less than the threshold (Sth = 0.1714) of the standard deviations, as described above.
When the standard deviations after the correction become equal to or less than the threshold in step S133 (S133 → No), the measuring processor 213 performs the process of step S141. In step S141, the measuring processor 213 performs voltage calibration on the corrected calibration point 521 using the corrected quadrupole RF voltage as an initial value (third step). Specifically, the measurement processing unit 213 reacquires the spectrum 501 by performing the above-described scan using the corrected quadrupole RF voltage as an initial value. Then, the measuring processor 213 estimates the quadrupole RF voltage corresponding to the peak values of the calibration ions indicated by the spectrum 501a portion by the correction based on the reacquired spectrum 501. In this way, the correct quadrupole RF voltage can be obtained. The processing performed in step S141 will be described later.
In addition, in the step S133, when the corrected standard deviations become larger than the threshold (S133 → Yes), the correction processing unit 212 repeats the processing in and after the step S112 until the standard deviations become equal to or smaller than the threshold. However, when the number of loops becomes larger than the predetermined number (hmax), the correction processing unit 212 outputs an error (S151).
Referring to Fig. 9A, the corrected quadrupole RF voltage at the calibration point 521 numbered "6" 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) (= about 0. 2Da (0.332 × 10 - 24g)). Accordingly, in the voltage calibration using the corrected quadrupole RF voltage as the initial value, the peak value derived from the correct calibration ion can be acquired as described above. Further, as shown by the broken line and the white circle in Fig. 9B, the deviation is also reduced.
In the equation (1) showing the slope between the calibration points, the deviation of the amplitude of the quadrupole RF voltage is reflected more sharply as the m / z difference (mi + 1-mi) is smaller. In many cases, the calibration sample is selected so that the calibration points 521 are arranged at uniform m/z intervals. However, there are cases where a calibration sample having non-uniform m/z intervals is selected. In this way, when the intervals between the calibration points 521m / z are not uniform, the m / z differences (mi + 1-mi) between the calibration points may be weighted when calculating the standard deviations.
In the present embodiment, the voltage calibration (S141 in Fig. 8) is performed after the correction of the calibration point 521 is performed, but the present invention is not limited thereto. After the correction of the calibration point 521 is performed, only the result of the correction (that is, the corrected quadrupole RF voltage) may be stored in the storage 220, and the voltage calibration may be performed as a process different from the correction of the calibration point 521.

(Voltage Calibration)

Fig. 10 is a diagram illustrating a voltage calibration method. Reference is made to Fig. 1 as appropriate. Fig. 10 is an enlarged view of the vicinity of the spectrum 501a and the spectrum 502 in the graph of the quadrupole RF voltage-ion signal intensity relation shown in Fig. 5. The process shown in Fig. 10 is performed by the measuring unit 213 shown in Fig. 1 in step S141 of 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 numeral 531) calculated by the corrected calibration point 521. That is, the scan range 511 is gradually expanded from the narrow scan range 511 such as the scan range 511a portion with the quadrupole RF voltage (reference numeral 531) estimated by the correction of the calibration point 521 as the center. In the number "6" in Fig. 9A, it is shown 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 numeral 531) calculated by the corrected calibration point 521 is shown at a position shifted from the spectrum 501a central portion.
The scan range 551 is changed every time measurement is performed. That is, the scan range 511 is gradually expanded from the scan range 511a to the scan range 511c. Then, the scan range 511 is gradually enlarged until the spectrum 501a of the calibration ions enters the scan range 511c. By starting the measurement from the narrow scan range 511 in this manner, it is possible to prevent the spectrum 502a from being scanned. Therefore, it is possible to prevent the peak of the spectrum 501a from being mistaken for the peak of the spectrum 502 due to the adjacent impurity ion. It is also possible to obtain the true 501a of the spectral center.
In this way, in the voltage calibration, the measurement processing unit 213 measures the calibration ions in the mass spectrometer 100 in the scan range 511 centered on the quadrupole RF voltage calculated by the corrected calibration point 521. At this time, the measuring processor 213 changes the scan range 511 so that the scan range 511 gradually becomes a wider range every time the measuring is performed, as illustrated in the scan ranges 511a to 511c in Fig. 10.
Although the quadrupole EF voltages corresponding to the peak values of the spectrum 501a are estimated by the calibration points 521, the rescan as shown in Fig. 10 is performed. This is because, as described above, the quadrupole RF voltage value estimated by the correction does not necessarily indicate a correct value as indicated by the number "6" of the calibration point 521 in Fig. 9A.
According to the first embodiment, when performing voltage calibration, even if there is a contaminant ion having m / z adjacent to the calibration point 521, it is possible to correct the mistaking of the peak of the contaminant ion and the peak of the calibration ion. This allows the determination of the exact quadrupole RF voltage originating from the calibration ions. As a result, when an unknown substance is subjected to mass spectrometry, mass spectrometry with high accuracy can be performed. Further, according to the first embodiment, even if there is only one misidentification of the peak, the correction of the calibration point 521 and the voltage calibration can be performed.

Second Embodiment

A second embodiment will be described below. The configuration of the mass spectrometry system 1 in the second embodiment is the same as the configuration shown in Fig. 1, and thus illustration and description thereof in the second embodiment will be omitted. In Fig. 12, the same symbols are given to the same components as those in Fig. 7B, and the description thereof is omitted.
Hereinafter, the process performed in the second embodiment will be described with reference to Figs. 11 and 12. Fig. 11 is a flowchart showing a procedure of a 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, step numbers are those shown in Fig. 11. In Fig. 11, the same step numbers are given to the same steps as those in Fig. 8, and the description 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 with the threshold value based on the calculated slope. That is, in the first embodiment, the slope (ak) between the calibration points 521 is calculated one by one in the step S102 and the step S131 of Fig. 8. In contrast, in the second embodiment, the correction processing unit 212 obtains a straight line 701 close to all the calibration points 521 as illustrated in Fig. 12 by the least-squares method according to the following Equation (21). That is, the correction processing unit 212 calculates the slope and the 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 an intercept 711 calculated by applying the least-squares method to each of the calibration points 521. In this manner, in the second embodiment, the inclinations between the respective calibration points 521 are unified to the inclination obtained by the least-squares method.
Subsequently, the correction processing unit 212 calculates the deviation (Di) (S103A). In the second embodiment, the deviation (Di) is defined as the length of a 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 to the straight line 701 having the slope and intercept 711 for each of the calibration points 521. In this manner, in step S103A, the correction processing unit 212 calculates, as the deviation (Di), the distances (the lengths of the perpendicular lines 721) from the straight line 701 having the slope and the intercept 711 to the respective calibration points 512.
Thereafter, the correction processing unit 212 calculates the standard deviations (SD) of the deviations (Di) calculated in step S103A (S104A).
When the standard deviations (SD) of the deviations (Di) are larger than the thresholds (SD> Sth) set in advance (S105 → Yes), the correction processing unit 212 corrects the calibration points 521 based on the inclination. The procedure for correcting the calibration point 521 based on the inclination is the same as that of the first embodiment.
[Number 3] $slope = \frac{\sum (m_{i} - \bar{m}) (x_{i} - \bar{x})}{\sum {(x_{i} - \bar{x})}^{2}}$
In Equation (21), "slope" indicates a slope, and mi and xi indicate m / z and the quadrupole RF voltage as shown in Fig. 7A and Fig. 7B. The variables with a bar above m represent the mean of mi. The variables with a bar above x represent the average of xi (quadrupole RF voltage).
The correction of the calibration point 521 is performed by the following Equation (22). $Xi_cor = slope \cdot mi + b$
In Equation (22), xi _ cor represents 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. That is, the corrected calibration point 521 is corrected so as to be on the straight line 701 by the least squares method.
In step S121A of Fig. 11, the deviation (Di) is calculated in the same procedure as in step S103A. Although not shown in Fig. 11, the slope and intercept 711 are calculated in the same procedure as in the step S121A in the stage preceding the step S102A. Further, the step S131A is the same process as the step S102A, and the step S132A is the same process as the step S104A. Further, although not shown, the same processing as that of the step S131A is performed between the step S132A and the step S103A.
As described above, in the second embodiment, the mistaking of the peaks of the impurity ions and the 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 inclination between the calibration points 521 is calculated at once by the least-square method, as compared with the first embodiment in which the inclination between the calibration points 521 is calculated one by one. Therefore, the method shown in the second embodiment can be performed at high speed because the calculation is simpler than that of the method shown in the first embodiment.

Third Embodiment

Next, an example in which the calibration point correction process shown in the first embodiment and the second embodiment is applied to a mass spectrometry system 1a in which the time-of-flight mass spectrometer 400 is installed in the analyzing unit 103 will be shown with reference to Fig. 13. Fig. 13 is a diagram illustrating a configuration example of a mass spectrometry system 1a according to a third embodiment. The mass spectrometer 1a shown in the mass spectrometry system 100a shown in Fig. 13 is different from the mass spectrometry system 1 shown in Fig. 1 in the following points.

(A1) The time-of-flight mass spectrometer 400 is provided in the analyzing unit 103.
(A2) A power source 410 that applies a pulse voltage is connected to the pusher electrode 401 constituting the time-of-flight mass spectrometer 400.

The power supply 410 is controlled by a voltage controller 300. In Fig. 13, the same reference numerals are given to the same configurations as those in Fig. 1.
In the mass spectrometer 100a, ions generated by the ion source 151 are introduced into the first differentially pumping region 101 through the aperture 121, as in Fig. 1. As in Fig. 1, the first differential pumping region 101 is evacuated by the pump 111. Accordingly, the first differentially pumping region 101 is maintained at a vacuum level from 10Pa to 500Pa. The ions that have passed through the first differential pumping region 101 are introduced into the second differential pumping region 102 through the aperture 122. As in Fig. 1, the second differential pumping region 102 is pumped by the pump 112. Accordingly, the second differentially pumping region 102 is maintained at a vacuum level of 0. 1Pa to 10Pa. Further, as in Fig. 1, the second differential pumping region 102 is provided with an ion guide 130 for converging ions. The ions converged by the ion guide 130 pass through the aperture 123 and are introduced into the analysis unit 103 in which the time-of-flight mass spectrometer 400 is installed. As in Fig. 1, the analysis unit 103 is evacuated by the pump 113. Thus, the pressure in the analyzing section 103 is maintained at a pressure equal to or lower than 1E minus 5Pa.
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 extrusion electrode 401 by a power supply 410. By applying the pulse voltage, the pusher electrode 401 bends the traveling direction of a part of the ions incident from the ion guide 130 to a direction perpendicular to the incident direction of the ions. The deflected ions are directed 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 arrows in Fig. 13). The ions reflected by the reflector electrode 403 are detected by the detector 152. The time required 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, a spectrum 501 of the ions (see Fig. 5) can be obtained by plotting the signal intensity of the ions detected by the detector 152 against the time of flight.
In the time-of-flight mass spectrometer 400, a multi-channel plate type detector 152 is generally used as the detector 152. The detector 152 converts the detection intensity of the ions into an electrical signal (output signal), and sends the electrical signal to the data processing device 200. At this time, as in Fig. 1, the output signal output from the detector 152 is converted into digital data of a constant sampling period, and then sent to the data processing device 200. As in Fig. 1, the conversion into 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 transmitted digital data in the storage 220.
Even in the mass spectrometry system 1a as shown in Fig. 13, the calibration ions are measured, and the methods shown in the first embodiment and the second embodiment can be applied to the obtained spectrum 501 (see Fig. 5). At this time, the amplitude of the pulse voltage applied to the pusher electrode 401 is used instead of the quadrupole RF voltage of the first embodiment. That is, in the third embodiment, the pulse voltage is a voltage acquired as a result of measuring a plurality of calibration ions by the mass spectrometer 100. In the third embodiment, the quadrupole RF voltage axes of the m / z-quadrupole RF voltage relation graphs shown in Figs. 6 to 7B are pulse voltage axes.
In the mass spectrometry system 1a, when there is a contaminant ion whose m / z is adjacent to the calibration point 521, there is a possibility that the peak of the contaminant ion and the peak of the calibration ion are mistaken for each other. However, by using a pulse voltage instead of the quadrupole RF voltage of the first embodiment, the same processing as that of the first embodiment and the second embodiment can be performed. This makes it possible to correct the mistaking of the peaks. This makes it possible to obtain an accurate m/z value when an unknown substance is subjected to mass spectrometry.
The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the configurations described above. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. In addition, a part of the configuration of each embodiment can be added to, deleted from, or replaced with another configuration.
Further, a part or all of the above-described respective configurations, functions, plot processing unit 211, correction processing unit 212, measurement processing unit 213, storage 220, and the like may be realized by hardware by designing them with an integrated circuit, for example. As shown in Fig. 2, the above-described configurations, functions, and the like may be realized by software by a processor such as a CPU interpreting and executing a program for realizing each function. Information such as programs, tables, and files for implementing the functions may be stored in a hard disk (HD), a recording device such as a memory or a solid state drive (SSD), or a recording medium such as an integrated circuit (IC) card, a secure digital (SD) card, or a digital versatile disc (DVD).
In each embodiment, control lines and information lines considered to be necessary for description are illustrated, and all control lines and information lines in a product are not necessarily illustrated. In practice, it may be considered that almost all the configurations are connected to each other.

Description of Symbols

1, 1a Mass spectrometry system
100, 100a Mass spectrometer
140 Quadrupole mass filter
141, 141a to 141d Quadrupole rod electrodes
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 points (outliers)
701 Straight line (including slope)
711 Section
721 Perpendicular (deviation)
S101 Plot Processing (First Step)
S124 Correction (Second Step)
S141 Mass Calibration (Third Step)

Claims

A data processing device comprising:
a plot processing unit configured to plot voltages acquired as a result of measuring a plurality of calibration ions having known m/z values by a mass spectrometer and the m/z values of the respective calibration ions as calibration points on coordinates having the voltages and the m/z values as coordinate axes; and

a correction processing unit configured to correct the calibration points by correcting outliers if there are outliers for the respective calibration points.
The data processing device according to claim 1, further comprising
a measurement processing unit that performs measurement of the calibration ions by the mass spectrometer in a voltage range centered on the voltage calculated by the corrected calibration point.
The data processing device according to claim 2, wherein the measurement processing unit changes the voltage range so that the voltage range gradually becomes a wider range every time the measurement is performed.
The data processing device according to claim 1, wherein the correction processing unit calculates a slope between the calibration points, calculates a deviation regarding each of the slopes, determines that there is the outlier when a standard deviation of the deviation is larger than a preset threshold value, and corrects the calibration point based on the slope.
The data processing device according to claim 1, wherein the correction processing unit calculates a slope and an intercept by applying a least squares method to each of the calibration points, calculates a distance from a straight line having the slope and the intercept as a deviation for each of the calibration points, and corrects the calibration point based on the slope when a standard deviation of the deviation is larger than a preset threshold value.
A mass spectrometry system comprising:
a mass spectrometer;

a plot processing unit configured to plot voltages acquired as a result of measuring a plurality of calibration ions having known m/z values by the mass spectrometer and the m/z values of the respective calibration ions as calibration points on coordinates having the voltages and the m/z values as coordinate axes; and

a correction processing unit configured to correct the calibration points by correcting outliers if there are outliers for the respective calibration points.
The mass spectrometry system according to claim 6, further comprising
a measurement processing unit that measures the calibration ions by the mass spectrometer in a voltage range centered on the voltage calculated by the corrected calibration point.
The mass spectrometry system according to claim 6, wherein the mass spectrometer has a quadrupole mass filter or a time-of-flight mass spectrometer in an analysis unit.
A mass spectrometry data processing method comprising:
a first step of plotting, by a data processing device, voltages acquired as a result of measuring a plurality of calibration ions having known m/z values by a mass spectrometry device and the m/z values of the respective calibration ions as calibration points on coordinates having the voltages and the m/z values as coordinate axes; and

a second step of correcting the calibration points by correcting outliers if there are outliers for the respective calibration points.
The mass analysis data processing method according to claim 9, further comprising
a third step of measuring the calibration ions by the mass spectrometer in a voltage range centered on the voltage calculated by the corrected calibration point.