JP6680230B2 - Mass spectrometer and mass spectrometry method - Google Patents

Description

  The present invention relates to a mass spectroscope and a mass spectrometric method, and more particularly to a technique for solving a problem caused by contamination of electrodes and the like that occurs when the mass spectroscope is used for a long period of time.

Generally, a mass spectrometer is an ion source that ionizes a compound in a sample, a mass separator such as a quadrupole mass filter that separates ions derived from the compound according to the mass-to-charge ratio (m / z), and the separated ions. A detector for detecting, etc. are provided. In the case of a gas chromatograph mass spectrometer (GC-MS) which is a combination of a gas chromatograph and a mass spectrometer, in order to ionize a compound in a gas sample, an electron ionization (EI = Electron Ionization) method or chemical ionization (CI = Chemical) is used. An ion source according to an ionization method such as an Ionization method or a negative chemical ionization ( NCI = Negative Chemical Ionization) method is used.

  As disclosed in Patent Document 1 and the like, in a mass spectrometer in GC-MS, an ion source, a quadrupole mass filter, and a detector by an EI method are provided in a vacuum chamber maintained in a vacuum state by a vacuum pump. Are placed. When the sample gas is introduced into the ionization chamber of the ion source, the compounds in the sample gas come into contact with the thermoelectrons to be ionized. The generated ions are an electric field formed by the voltage applied to the repeller electrode installed in the ionization chamber, or an electric field formed by the voltage applied to the extraction electrode installed outside the ionization chamber. By one or both of them, it is extracted from the ionization chamber, converged by a lens electrode or the like, and sent to the quadrupole mass filter.

  In such a mass spectrometer, a compound such as a repeller electrode, an extraction electrode, or a lens electrode (hereinafter, collectively referred to as “ion transport electrode” because they all contribute to the transport of ions to the mass separator) The originating ions come into contact and adhere. When GC-MS is used for a certain period of time and the degree of contamination of the electrodes for ion transport increases, the charge-up on the electrodes increases, and the electric field formed by these electrodes is disturbed to cause quadrupole mass. The amount of ions reaching the filter is reduced. As a result, problems such as a decrease in detection sensitivity occur. Therefore, generally, when it is assumed that the ion transport electrode is contaminated, maintenance work such as disassembling the device and cleaning the electrode is performed.

  The degree of contamination of the electrode for ion transport can be estimated based on, for example, the usage time of GC-MS (integrated value of analysis time). However, in reality, the degree of progress of contamination of the ion transport electrode is considerably different depending on the type of the sample, the compound concentration in the sample, the analysis conditions, and the like. Therefore, even if the device is used for the same period of time, there are cases where the ion transport electrode is not contaminated so much that it needs to be cleaned, and conversely, the contamination is considerably severe. May not be able to perform maintenance work.

  On the other hand, it is desirable for an operator to visually check the degree of contamination of the ion transport electrode more reliably, but for that purpose, it is necessary to stop the operation of the vacuum pump and disassemble the apparatus. As a result of the check, if there is no dirt, it is necessary to assemble the device and return it to a state in which it can be analyzed, which is a waste of time and a burden on the operator.

JP, 2011-257333, A

  The present invention has been made to solve the above problems, and an object thereof is to accurately measure the degree of contamination of the ion transport electrode while maintaining the vacuum state in the chamber without disassembling the device. It is to provide a mass spectroscope and a mass spectrometric method that can be grasped.

A mass spectrometer according to the present invention made to solve the above-mentioned problems is an ion source that ionizes a compound in a sample, a mass separator that separates ions according to a mass-to-charge ratio, and the ion source An ion transport optical system including a plurality of electrodes forming an electric field for transporting the generated ions to the mass separator, and a mass spectrometer comprising:
a) The combination of voltages applied to the plurality of electrodes included in the ion transport optical system is such that the voltage applied to at least one of the plurality of electrodes is equal to or more than a predetermined voltage difference before and after the combination is changed. While changing so that each time a voltage of the different combination is applied, an analysis control unit that controls each unit to repeatedly perform the measurement for the same compound in the sample,
b) rearrange the measurement results for the same compound respectively obtained under the combination of different applied voltages under the control of the analysis control unit in the order of increasing or decreasing the applied voltage to the at least one electrode, and applying the results. A measurement result processing unit that obtains a relationship between a change in voltage and a change in signal strength or sensitivity,
It is characterized by having.

Further, the mass spectrometry method according to the present invention made to solve the above problems is an ion source for ionizing a compound in a sample, a mass separator for separating ions according to a mass-to-charge ratio, and the ion source. An ion transport optical system including a plurality of electrodes forming an electric field for transporting the generated ions to the mass separator, and a mass spectrometric method using a mass spectroscope comprising:
a) The combination of voltages applied to the plurality of electrodes included in the ion transport optical system is such that the voltage applied to at least one of the plurality of electrodes is equal to or more than a predetermined voltage difference before and after the combination is changed. An analysis execution step of repeatedly performing measurement for the same compound in the sample each time a voltage of the different combination is applied, while changing so that there are cases.
b) rearrange the measurement results for the same compound respectively obtained under different combinations of applied voltages in the analysis execution step in the order of increasing or decreasing voltage applied to the at least one electrode, A measurement result processing step for obtaining the relationship between the change and the change in signal strength or sensitivity,
It is characterized by having.

  Here, the plurality of electrodes included in the ion transport optical system refers to electrodes that influence the behavior of the ions generated in the ion source when the ions move from the ion source to the mass separator. Therefore, for example, when the ion source is an ion source that ionizes the compound contained in the sample gas in the ionization chamber installed in a vacuum atmosphere by the EI method, the CI method, the NCI method, etc., it is included in the ion transport optical system. The plurality of electrodes are at least one of a repeller electrode arranged in the ionization chamber for pushing out ions from the ionization chamber and an extraction electrode arranged outside the ionization chamber for extracting ions from the ionization chamber. Can be configured to include.

  In the mass spectrometer according to the present invention, the analysis control unit sequentially applies voltages having different combinations of voltage values to the plurality of electrodes included in the ion transport optical system. At this time, the voltage applied to at least one of the plurality of electrodes is set to be a predetermined voltage difference or more at least once before and after changing the combination. Then, each time a voltage due to the different combination is applied to each electrode, by controlling each unit so as to repeatedly perform the measurement for the same ion species derived from the same compound in the sample, for example, a specific compound derived from the compound The signal intensities of the ions each having a mass-to-charge ratio are acquired. The predetermined voltage difference can be experimentally determined in advance. For example, V1, V1 + ΔV, V1 + 2ΔV, ..., V2−ΔV, V2, which are set by dividing a suitably determined voltage range V1 to V2 by a predetermined voltage step width ΔV, are randomly rearranged to the at least one electrode. A voltage may be applied.

  When the voltage value to be applied in this manner is randomly determined, the voltage applied to the at least one electrode does not increase or decrease stepwise when repeatedly measuring the same compound in the sample, The voltage increase and the voltage decrease appear irregularly, and the voltage difference before and after the voltage change may be relatively large or small. The measurement result processing unit rearranges the measurement results thus obtained, that is, the signal intensity of ions derived from a specific compound, in the order of increasing or decreasing the applied voltage to the at least one electrode, and the applied voltage. Determine the relationship with signal strength or sensitivity.

  When an electrode included in the ion transport optical system is contaminated due to adhesion of ions or the like, charge-up occurs, so that the electric field does not sufficiently follow the change in the applied voltage even if the applied voltage to the electrode changes. When the applied voltage to the electrode is increased or decreased stepwise (for example, by the voltage step width ΔV), the change of the electric field is originally small, and the influence on the behavior of the ions is small. On the other hand, when the applied voltage to the electrode is suddenly increased (that is, with a large voltage difference) or decreased, the influence of the electric field not following is relatively large, and the behavior of the ions is largely changed. As a result, the smoothness of the curve showing the relationship between the voltage and the signal strength or sensitivity obtained by rearranging the signal strength of the ions derived from the specific compound in the order in which the applied voltage increases or decreases as described above, is impaired. Measurement results are clearly observed that deviate from the curve.

  Therefore, whether the curve showing the relationship between the applied voltage and the signal strength or sensitivity obtained as described above is sufficiently smooth, or whether there is a signal strength value that does not follow the curve, etc. By making the determination, it can be determined whether or not the charge-up phenomenon is occurring in the electrodes included in the ion transport optical system. If it can be determined that the charge-up phenomenon has occurred, there is a high possibility that the electrodes are dirty. Therefore, the user disassembles the device and performs or requests the work of cleaning the electrodes included in the ion transport optical system, for example. You can take the action of.

  In the mass spectrometer according to the present invention, after the measurement result processing unit obtains the relationship between the change in applied voltage and the change in signal strength or sensitivity, a graph showing the relationship is displayed on the screen of the display unit, and the user By confirming this, the user can determine whether or not the charge-up phenomenon has occurred.

  Further, in the mass spectrometer according to the present invention, preferably, based on the relationship between the change in the applied voltage and the change in the signal strength or the sensitivity obtained by the measurement result processing unit, the signal strength or the sensitivity of the change in the applied voltage is measured. It is preferable to further include a determination index value calculation unit that calculates an index value indicating the variation.

  Furthermore, in the mass spectrometer according to the present invention, based on the index value calculated by the determination index value calculation unit, a contamination determination unit that determines the degree of contamination of the plurality of electrodes included in the ion transport optical system. The configuration may further include.

  According to this configuration, as described above, the user himself / herself does not judge whether or not the charge-up phenomenon is occurring to estimate the degree of contamination, but the contamination determination unit automatically determines the degree of contamination of the electrodes. The result can be shown to the user. As a result, the burden on the user is reduced, and it is possible to accurately determine whether or not the electrode is dirty enough to be washed, without depending on experience or skill.

  Of course, the index value calculated by the determination index value calculation unit may be presented to the user, and the user himself / herself may determine the degree of dirt based on the index value.

  According to the mass spectrometer and the mass spectrometry method of the present invention, the degree of contamination of the ion transport electrode can be accurately measured without disassembling the device and without stopping the operation of the vacuum pump that evacuates the chamber. Can be grasped. This allows the user to accurately determine when to perform maintenance work for cleaning those electrodes, save inefficient work such as visually checking the degree of electrode contamination, and improve the efficiency of analysis work. Can be achieved.

1 is a configuration diagram of a main part of a mass spectrometer that is an embodiment of the present invention. 5 is a flowchart showing the procedure of measurement and processing for charge-up determination in the mass spectrometer of the present embodiment. The figure which shows the pattern of the combination of the applied voltage to the electrodes L1-L4 in the experiment for confirming a charge-up phenomenon. 6 is a graph showing a schematic relationship between the voltage applied to the electrode L1 and the sensitivity when the electrodes L1 to L4 are not contaminated. 6 is a graph showing a schematic relationship between the voltage applied to the electrode L1 and the sensitivity when the electrodes L1 to L4 are soiled.

A mass spectrometer which is an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a configuration diagram of a main part of the mass spectrometer according to the present embodiment, and FIG. 2 is a flow chart showing a measurement and processing procedure for charge-up determination in the mass spectrometer according to the present embodiment.

As shown in FIG. 1, the mass spectrometer of the present embodiment includes a measurement unit 1, an analog-digital conversion unit (ADC) 2, a data processing unit 3, a voltage generation unit 4, an analysis control unit 5, and a main unit. The control unit 6, the input unit 7, and the display unit 8 are provided.
The measurement unit 1 includes an ion source 12, an ion lens 14, a quadrupole mass filter 15, and a detector 16 inside a chamber 10 that is evacuated by a vacuum pump 11. The ion source 12 includes an ionization chamber 121 to which the sample introduction tube 13 is connected, a filament 122, a trap electrode 123, and a repeller electrode 124. The ion lens 14 includes first to third ring-shaped lens electrodes 14a, 14b, and 14c in order from the ion source 12 side. The data processing unit 3 includes, as functional blocks, a data storage unit 31, a voltage-intensity relation curve creation unit 32, an intensity dispersion amount calculation unit 33, and a charge-up determination unit 34. The analysis control unit 5 includes a charge-up determination time control unit 51 as a functional block.

  Note that at least some of the functions of the data processing unit 3, the analysis control unit 5, and the main control unit 6 are realized by executing dedicated control / processing software preinstalled in a general-purpose personal computer on the computer. It can be configured to be.

Next, the measurement operation of the measuring unit 1 of the mass spectrometer of the present embodiment will be briefly described.
For example, the sample gas that has passed through a column of a gas chromatograph (not shown) is introduced into the ionization chamber 121 through the sample introduction pipe 13. A thermoelectron flow from the filament 122 toward the trap electrode 123 is formed in the ionization chamber 121, and the compound in the introduced sample gas is ionized by coming into contact with the thermoelectrons. The generated ion derived from the compound is formed by the voltage applied from the voltage generating section 4 to the first lens electrode 14a similarly to the action of the electric field formed by the voltage applied by the voltage generating section 4 to the repeller electrode 124. Either or both of the action of the electric field pulls the ionization chamber 121 to the right. Then, the ions are introduced into the space in the long axis direction of the quadrupole mass filter 15 while being converged by the electric field formed by the voltage applied from the voltage generator 4 to the ion lens 14.

  A voltage obtained by superimposing a DC voltage and a high frequency voltage is applied from a voltage generator (not shown) to the plurality of rod electrodes that configure the quadrupole mass filter 15, and ions having a specific mass-to-charge ratio according to the applied voltage are applied. Only passes through the longitudinal space. Other ion species diverge and disappear while passing through the quadrupole mass filter 15. The detector 16 outputs a detection signal according to the amount of ions that have passed through the quadrupole mass filter 15.

  Ions come into contact with the repeller electrode 124 arranged in the ionization chamber 121 and the lens electrodes 14a to 14c arranged in the immediate vicinity of the ion outlet of the ionization chamber 121, so that the surfaces of these electrodes 124 and 14a to 14c contact the electrodes. Dirt due to ions easily accumulates. In the mass spectrometer of the present embodiment, the degree of contamination of these electrodes 124, 14a to 14c is determined by the characteristic method described below.

First, the principle of the method for determining the degree of contamination of the electrodes in the mass spectrometer of the present embodiment will be described.
In the following description, the repeller electrode 124 and the three lens electrodes 14a, 14b, 14c, which are involved in the behavior of the ions moving from the ion source 12 to the quadrupole mass filter 15, will be referred to as electrodes L1, L2, L3, L4, respectively. Is written. These electrodes are electrodes included in the ion transport optical system. When the DC voltage applied to the electrodes L1 to L4 is changed, the extraction efficiency of ions from the ionization chamber 121 and the passage efficiency of ions are changed, and thus the amount of ions that can reach the detector 16 is changed. Therefore, the detection sensitivity changes. Therefore, the applied voltage to each of the electrodes L1 to L4 is usually adjusted so that, for example, the detection sensitivity when measuring a predetermined standard sample is at or near the maximum. Generally, such adjustment is automatically performed by an auto tuning function installed in the mass spectrometer.

  When stains due to the adhesion of ions are deposited on the electrodes L1 to L4, the strength of the electric field and the three-dimensional shape of the potential gradient are changed even when the same voltage as when there is no stain is applied, and the detection sensitivity is increased. Is expected to change. Therefore, the present inventor investigated the relationship between the applied voltage to each of the electrodes L1 to L4 and the detection sensitivity by the following experiment.

[Experiment 1]
FIG. 3 is a diagram showing patterns of combinations of applied voltages to the electrodes L2 to L4. The voltage applied to the electrodes L2 to L4 was set in nine combinations as shown in FIG. 3, and the voltage applied to the electrode L1 was changed from -15V to + 15V in 0.1V step width for each combination. That is, the total number of combinations of applied voltages to the electrodes L1 to L4 is 300 × 9 = 2700. For each of these 2700 combinations, PFTBA (perfluorotributylamine), which is well known as a standard sample, was introduced into the ionization chamber 121, and the peak intensity of the ion of m / z: 69 derived from the compound was measured. However, at the time of measurement, the measurement was performed in the order in which 2700 combinations of applied voltages were randomly rearranged. Therefore, for example, the voltage applied to the electrode L1 does not gradually change in a 0.1 V step width from −15 V → −14.9 V → −14.8 V → ..., For example, −15 V → + 12.8 V → -11. The applied voltage may suddenly change to 5 V or the like. In this way, after obtaining peak intensity data of ions derived from PFTBA for all 2700 combinations of applied voltages, the data are divided into 9 combinations shown in FIG. 3, and further applied to the electrode L1 in each combination. The data is rearranged according to the increasing order of the voltage (that is, in the order of −15V → −14.9V → −14.8V → ...), and a graph showing the relationship between the change of the voltage applied to the electrode L1 and the change of the peak intensity is shown. Created.

4, when the dirt on the electrode L1~L4 has not occurred, = (voltage applied to the electrode L2, applied voltage to the electrode L3, the voltage applied to the electrode L4) (- 20,5, -50) , (-20,0, -40), (-40,5, -40), (-40,0, -45) four combinations of voltage applied to the electrode L1 and peak intensity (vertical in FIG. 4). The axis is shown by sensitivity, but it is substantially the same as the peak intensity). On the other hand, FIG. 5 is a graph schematically showing the relationship between the applied voltage to the electrode L1 and the peak intensity for the combination of (-40, 5, -40) when the electrodes L1 to L4 are dirty. . In FIG. 4, the shape of the curve showing the relationship between the change in the applied voltage to the electrode L1 and the change in the sensitivity is different depending on the combination of the applied voltages to the electrodes L2 to L4, but the sensitivity to the change in the applied voltage to the electrode L1 is All changes are smooth curves. On the other hand, looking at FIG. 5, although the schematic shape of the curve showing the relationship between the applied voltage to the electrode L1 and the sensitivity is almost the same as the result of FIG. 4, it does not follow this curve, that is, the sensitivity. There are not a few plot points that appear at positions greatly deviated from this curve. From this result, in a specific combination of applied voltages, more strictly speaking, when the change from one combination of applied voltages to another combination is in a specific state, a large variation (discontinuity) occurs in sensitivity. I can guess that.

[Experiment 2]
Next, the phenomenon of variation in sensitivity observed when the electrodes L1 to L4 are contaminated, which is confirmed in Experiment 1 above, occurs in a combination of applied voltages such that the applied voltage to the electrode L1 changes rapidly. The following experiment was conducted in order to verify whether it was a thing.
In this experiment, (applied voltage to electrode L2, applied voltage to electrode L3. Applied voltage to electrode L4) was set to two types (-40, 0, -45) and (-40, 0, -40). The voltage applied to the electrode L1 was changed in the voltage range from -15V to + 15V by the following procedure.
<Condition A> The voltage is sequentially increased from -15V to + 15V by 0.1V step width.
<Condition B> The voltage value in steps of 0.1V step over the voltage range of −15V to + 15V is randomly replaced. This is the same method of changing the applied voltage as in Experiment 1.
<Condition C> The time interval for continuous measurement is widened in the same order as in Condition B.
<Condition D> The voltage applied to the electrode L1 is temporarily set to 0 V for a short time in the same order as in Condition B and between successive measurements.
<Condition E> The measurement is performed in the reverse order of Condition B.

  When the electrodes L1 to L4 are contaminated, the measurement is repeatedly performed for each of the above conditions A to E to obtain the peak intensity data of the ions derived from PFTBA, and then, as in FIGS. The data was rearranged and graphed according to the increasing order of the applied voltage to L1. As a result, under the condition A, the curve showing the relationship between the voltage applied to the electrode L1 and the sensitivity was smooth, and no significant variation in sensitivity was observed. On the other hand, in the conditions B to D, almost the same variations in sensitivity were observed. On the other hand, in condition E, a variation in sensitivity that is different from conditions B to D was observed.

  From the results of this experiment 2, the phenomenon of variation in the sensitivity confirmed in the above experiment 1 is reproduced when the change of the voltage applied to the electrode L1 is large, and this phenomenon occurs even if the time interval between consecutive measurements is increased. It was confirmed that it would not be resolved. This suggests that the disturbance of the electric field is hardly eliminated even if the time interval between the measurements is increased because the charge is generated in the electrode L1. It was also confirmed that, even if the voltage applied to the electrode L1 was once set to 0 V, the variation in sensitivity could not be eliminated between the measurements. This also suggests that the charge up at the electrode L1 causes the disturbance of the electric field to be hardly eliminated even if the applied voltage is 0 V for a short time between the measurements.

[Experiment 3]
After thoroughly cleaning the electrodes L1 to L4 of the device in which the sensitivity variation phenomenon as described above occurs, measurement was performed according to the procedure of condition B, and a graph as shown in FIG. 5 was created. Variations are no longer observed. From this, it can be said that when the electrodes L1 to L4 are contaminated, the sensitivities vary in a specific combination of the voltages applied to the electrodes L1 to L4. In other words, for example, the measurement is performed while changing the applied voltage in the same procedure as the condition B, and it is determined whether the sensitivity change with respect to the change of the applied voltage to the electrode L1 is smooth or the sensitivity varies. This makes it possible to determine whether or not the electrodes L1 to L4 are charged up, that is, how dirty the electrodes L1 to L4 are. In the mass spectrometer of the present embodiment, the degree of contamination of the electrodes L1 to L4, that is, the repeller electrode 124 and the lens electrodes 14a to 14c is determined by utilizing such an experimentally confirmed phenomenon.

That is, in the mass spectrometer of the present embodiment, the pattern of the combination of applied voltages capable of confirming the above-mentioned sensitivity variation phenomenon is set in the internal memory of the charge-up determination time control unit 51 in advance.
Specifically, for example, one or a plurality of combinations of applied voltages of the electrodes L2 to L4 in which variations in sensitivity are observed relatively conspicuously are selected from the nine combinations shown in FIG. 3, and the electrode L1 in the combination is selected. 300 kinds of applied voltages (voltages with a voltage range of −15 V to +15 V in 0.1 V step width) are randomized and stored in the internal memory as a combination pattern of applied voltages.

  When it is desired to confirm the degree of contamination of the repeller electrode 124 and the lens electrodes 14a to 14c in the mass spectrometer of the present embodiment, the user performs a predetermined operation from the input unit 7. Then, in response to the instruction from the main control unit 6 that has received this operation, the charge-up determination time control unit 51 reads the combination pattern of the applied voltages from the internal memory and sets it as one of the measurement conditions (step S1).

  The charge-up determination time control unit 51 controls the voltage generation unit 4 to sequentially change the applied voltage to the repeller electrode 124 and the lens electrodes 14a to 14c in accordance with the combination pattern of the applied voltages, and each time the applied voltage is changed. , The measurement unit 1 is controlled so as to acquire peak intensity data of ions derived from a predetermined compound such as PFTBA (step S2). The standard sample such as PFTBA can be supplied into the ionization chamber 121 through a dedicated sample introduction pipe different from the sample introduction pipe 13 for introducing the sample gas from the gas chromatograph or the like.

  The peak intensity data for different combinations of applied voltages as described above is temporarily stored in the data storage unit 31. The voltage-intensity relation curve creating unit 32 reads out the data from the data storage unit 31 and applies the same voltage to the lens electrodes 14a to 14c (the above electrodes L2 to L4) and to the repeller electrode 124 (the above electrode L1). By rearranging the peak intensity data with different applied voltages according to the increasing order of the applied voltage, a curve showing the relationship between the change of the applied voltage and the change of the peak intensity as shown in FIGS. 4 and 5 is created ( Step S3).

  Next, the intensity dispersion amount calculation unit 33 calculates an index value indicating the degree of variation of data points (peak intensity data) that do not follow the slope of the curve created in step S3 (step S4). Specifically, for example, the shape of the curve may be estimated by smoothing processing based on each data point, the error of each data point with respect to the estimated curve may be obtained, and the integrated value of the error may be calculated. Further, when the sensitivity curve is calculated by regression using the least squares method, the coefficient of determination can be used as an index for determining the degree of fit of the regression equation. In this case, if the coefficient of determination is large, it can be considered that the regression is not performed properly or there are many outliers. Since the variation in sensitivity described above indicates that there are many outliers, the coefficient of determination can be used as one determination index. Of course, not limited to these, the index value indicating the degree of variation (discontinuity) in sensitivity or signal intensity can be obtained by various algorithms.

The charge-up determination unit 34 compares the index value with a predetermined threshold value, and when the index value exceeds the threshold value, the degree of charge-up exceeds the allowable range, that is, the repeller electrode 124 and the lens electrode 14a. It is determined that there is a high possibility that at least one of the stains 14 to 14c is highly contaminated (step S5). Then, the charge-up determination unit 34 displays the determination result on the screen of the display unit 8 through the main control unit 6 (step S6).
The user may confirm this determination result and request a service person or the like to disassemble and clean the device if necessary.

As can be seen from FIGS. 4 and 5, since the degree of charge-up can be determined from the graph showing the relationship between the change in applied voltage and the change in peak intensity, this graph is displayed on the screen of the display unit 8 . Alternatively, the user may check the graph and determine the necessity of disassembling and cleaning the device. Alternatively, the index value calculated in step S4 may be displayed as it is, and the user may judge the necessity of disassembling and cleaning the device based on the numerical value.

In the above-mentioned examples, the present invention is applied to a mass spectrometer that ionizes and mass-analyzes a compound in a gaseous sample, but the present invention ionizes the compound in a liquid or solid sample. It can also be applied to a mass spectrometer that performs mass spectrometry.
For example, in an atmospheric pressure ionization mass spectrometer equipped with an ion source by an electrospray ionization (ESI) method, an atmospheric pressure chemical ionization (APCI) method, etc., the ionization chamber is placed in a vacuum chamber next to the ionization chamber at about atmospheric pressure. The lens electrodes and the like that compose the ion lens are easily contaminated by the adhesion of ions and sample droplets. Even in such a mass spectrometer, it is obvious that the degree of contamination of the lens electrode or the like can be determined by the same method as described above.

  Furthermore, the above embodiment is an example of the present invention, and it is apparent that, in addition to the above modifications, appropriate modifications, changes, and additions can be made within the scope of the gist of the present invention and still fall within the scope of the claims of the present application. Is.

DESCRIPTION OF SYMBOLS 1 ... Measuring part 10 ... Chamber 11 ... Vacuum pump 12 ... Ion source 121 ... Ionization chamber 122 ... Filament 123 ... Trap electrode 124 ... Repeller electrode 13 ... Sample introduction tube 14 ... Ion lens 14a, 14b, 14c ... Lens electrode 15 ... Four Double pole mass filter 16 ... Detector 3 ... Data processing unit 31 ... Data storage unit 32 ... Intensity relation curve creation unit 33 ... Intensity dispersion amount calculation unit 34 ... Charge-up determination unit 4 ... Voltage generation unit 5 ... Analysis control unit 51 ... Charge-up determination control unit 6 ... Main control unit 7 ... Input unit 8 ... Display unit

Claims (5)

An ion source for ionizing the compound in the sample, a mass separator for separating the ions according to the mass-to-charge ratio, and a plurality of electrodes forming an electric field for transporting the ions generated by the ion source to the mass separator. An ion transport optical system including:
a) The combination of voltages applied to the plurality of electrodes included in the ion transport optical system is such that the voltage applied to at least one of the plurality of electrodes is equal to or more than a predetermined voltage difference before and after the combination is changed. While changing so that each time a voltage of the different combination is applied, an analysis control unit that controls each unit to repeatedly perform the measurement for the same compound in the sample,
b) Rearrange the measurement results for the same compound obtained under the combination of different applied voltages under the control of the analysis control unit in the order of increasing or decreasing the applied voltage to the at least one electrode, and applying the applied voltage. A measurement result processing unit that obtains a relationship between a change in voltage and a change in signal strength or sensitivity,
A mass spectrometer, comprising: The mass spectrometer according to claim 1, wherein
Based on the relationship between the change of the applied voltage and the change of the signal strength or the sensitivity obtained by the measurement result processing unit, a determination index value calculation unit that calculates an index value indicating the variation of the signal strength or the sensitivity with respect to the change of the applied voltage. A mass spectrometer, further comprising: The mass spectrometer according to claim 2, wherein
The mass spectrometer, further comprising a stain determination unit that determines the degree of contamination of a plurality of electrodes included in the ion transport optical system based on the index value calculated by the determination index value calculation unit. The mass spectrometer according to any one of claims 1 to 3,
The ion source is an ion source that ionizes a compound contained in a sample gas in an ionization chamber installed in a vacuum atmosphere,
A plurality of electrodes included in the ion transport optical system are a repeller electrode arranged in the ionization chamber for pushing out ions from the ionization chamber, and an ion arranged outside the ionization chamber, for removing ions from the ionization chamber. A mass spectrometer, comprising at least one of an extraction electrode for extraction. An ion source for ionizing the compound in the sample, a mass separator for separating the ions according to the mass-to-charge ratio, and a plurality of electrodes forming an electric field for transporting the ions generated by the ion source to the mass separator. A mass spectrometric method using an ion transport optical system including the mass spectroscope, comprising:
a) The combination of voltages applied to the plurality of electrodes included in the ion transport optical system is such that the voltage applied to at least one of the plurality of electrodes is equal to or more than a predetermined voltage difference before and after the combination is changed. An analysis execution step of repeatedly performing measurement for the same compound in the sample each time a voltage of the different combination is applied, while changing so that there are cases.
b) rearrange the measurement results for the same compound respectively obtained under different combinations of applied voltages in the analysis execution step in the order of increasing or decreasing voltage applied to the at least one electrode, A measurement result processing step for obtaining the relationship between the change and the change in signal strength or sensitivity,
A mass spectrometric method comprising:

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