JP6540298B2 - Multi-component simultaneous analysis method and mass spectrometer using mass spectrometry - Google Patents

Description

  The present invention relates to a multicomponent simultaneous analysis method for analyzing a large number of compounds using a mass spectrometer and a mass spectrometer therefor, and in particular, a gas chromatograph (GC), a liquid chromatograph (LC) and a mass spectrometer The present invention relates to an analysis method and mass spectrometer suitable for performing multicomponent simultaneous analysis in a chromatograph mass spectrometer combined with (MS).

  In recent years, gas chromatograph mass spectrometer (GC-MS) and liquid chromatograph mass spectrometer (LC-MS) have been used in various fields such as pesticide residue inspection in food, pollutant inspection in environmental water, and toxicological inspection. Multicomponent analysis is used. For example, in multi-component simultaneous analysis targeting hundreds or more of many compounds, a plurality of compounds are often not sufficiently separated in GC or LC, and other compounds or unwanted contaminants that elute at the same time are overlapped. In order to avoid the influence of etc. as much as possible, a tandem mass spectrometer such as a triple quadrupole mass spectrometer or a Q-TOF mass spectrometer is often used as a mass spectrometer.

  In multi-component simultaneous analysis in GC-MS and LC-MS using a tandem mass spectrometer, usually, mass-to-charge ratio of precursor ion and product ion for multiple reactive ion monitoring (MRM) measurement for each compound to be measured The combination with the mass to charge ratio, that is, the MRM transition is set as the ion to be measured. Then, the MRM measurement is performed under the MRM transition corresponding to the compound according to the time (a retention time in GC or LC) at which a certain compound to be measured is introduced into the mass spectrometer, and the compound is derived from the compound The signal intensity of product ions is detected.

  In order to obtain accurate results in such analysis, it is necessary to set an appropriate MRM transition for each compound. Also, in a triple quadrupole mass spectrometer or a Q-TOF mass spectrometer, precursor ions are cleaved by collision induced dissociation (CID) in a collision cell, but dissociation is caused by collision energy (CE) given to the precursor ions. Efficiency is different. Therefore, it is necessary to set an appropriate collision energy as an MRM measurement condition.

  Conventionally, as disclosed in, for example, Non-Patent Document 1, a function of searching for an optimum MRM transition for a compound whose MRM transition is unknown and automatically searching for an optimum collision energy corresponding to the MRM transition is disclosed. There is known a mass spectrometer having the same. By utilizing such functions, it is possible to automatically search for the optimum MRM transition and collision energy etc. corresponding to a plurality of measurement target compounds, and based on the result, the data necessary for quantifying the compounds contained in the sample A control sequence for acquisition can be easily created.

  In the automatic search of MRM transition and collision energy as described above, in general, the MRM transition or collision is performed so that the detection sensitivity is the best for each compound, that is, the signal strength obtained by the detector is the maximum. Energy is determined. Also, instead of such an automatic search, it is general to search for a collision energy value that maximizes the signal strength even when an operator manually determines the optimum collision energy as described in, for example, Patent Document 1 It is.

  However, in the multi-component simultaneous analysis as described above, in some cases, it may not be possible to appropriately measure the MRM transition or collision energy which is determined so as to obtain the best detection sensitivity for each compound. For example, in a pesticide residue test based on a positive list, the concentration to be measured largely differs depending on the compound to be measured, or the signal intensity obtained largely differs depending on the compound to be measured even if the component concentration in the sample is the same. There is something to do. In such a case, setting a measurement condition other than the MRM transition or collision energy such that a compound having a low signal intensity or a low concentration to be measured is detected with sufficient sensitivity can obtain a high signal intensity or a concentration to be measured For high compounds, the signal may be saturated at the detector. Conversely, when setting measurement conditions other than MRM transition and collision energy so that compounds with high signal strength or high concentration of measurement target are detected with sufficient sensitivity, only low signal strength can be obtained or concentration of measurement target is low For compounds, the signal may be too small to allow accurate quantitation.

  In order to avoid this, in the conventional multi-component simultaneous analysis, a large number of measurement target compounds are divided into a plurality of groups according to the difference in signal intensity and the difference in measurement target concentration, and appropriate measurement conditions are set for each group. The measurement was performed by injecting the sample multiple times. However, such multiple measurements require a larger amount of sample. In addition, the consumption of the mobile phase (carrier gas in GC and eluent in LC) used in GC and LC also increases. Also, as a matter of course, the time required for the measurement also increases, and the throughput of the analysis decreases and the cost increases.

JP, 2013-234859, A

Application Data Sheet No. 98 Automatic Optimization of GC-MS Transition and Collision Energy, [online], Shimadzu Corporation, [July 6, 2015 search], Internet <URL: http: // www. an.shimadzu.co.jp/gcms/support/lib/pdf/laan-j-ms098.pdf>

  The present invention has been made in view of the above problems, and the object of the present invention is to measure the concentration of each measurement target compound when performing multi-component simultaneous analysis for quantifying each of a large number of measurement target compounds. Even if the signal intensities differ significantly or the signal intensities obtained differ significantly, mass spectrometry can be performed for high sensitivity measurement for trace compounds while avoiding signal saturation for high concentration compounds. It is an object of the present invention to provide a multicomponent simultaneous analysis method using the following, and a mass spectrometer used therefor.

The first aspect of the multicomponent simultaneous analysis method according to the present invention made to solve the above problems uses SIMS or MRM for each of a plurality of known compounds to be measured contained in a sample using a mass spectrometer. It is a multicomponent simultaneous analysis method of measuring each compound based on the result of measurement,
As a mass-to-charge ratio which is one of measurement conditions, which is a target of SIM measurement, or an MRM transition which is a target of MRM measurement, for a measurement target compound having a relatively high concentration to be measured or a relatively high measurement sensitivity, Among a plurality of mass-to-charge ratios or MRM transitions associated with the compound to be measured, the obtained signal strength uses a relatively low mass-to-charge ratio or MRM transition, and the concentration to be measured is relatively low or the measurement sensitivity Among the plurality of mass-to-charge ratios or MRM transitions associated with the to-be-measured compound, for the to-be-measured compounds having a relatively low It is characterized by

  In multicomponent simultaneous analysis in which the compound to be measured is known as described above, the range of the component concentration to be measured (in particular, the upper limit value of the range) is known for each compound. In addition, the signal intensity obtained when measuring a predetermined concentration of compound, that is, the measurement sensitivity can also be known by experimental measurement. Therefore, it is easy to know which of the compounds to be measured is relatively high or the measurement sensitivity is relatively high among a large number of compounds to be measured. On the other hand, in many cases, there are a plurality of MRM transitions derived from one measurement target compound. In addition, in mass spectrometers in which fragmentation easily occurs during ionization, such as mass spectrometers equipped with an ion source by electron ionization method generally used in GC-MS, there are also a plurality of mass-to-charge ratio values for SIM measurement. There are many things to do. In such a case, as a mass-to-charge ratio for SIM measurement or a transition for MRM measurement, it is general to use a mass-to-charge ratio or transition that provides the maximum signal strength (that is, the highest measurement sensitivity). However, in the multi-component simultaneous analysis method according to the first aspect of the present invention, the mass-to-charge ratio and MRM transition in which the signal intensity obtained is relatively low for compounds having high measurement sensitivity or high concentration to be measured. Dare to use the measurement.

  For example, by defining the transition in the MRM measurement in this way, even if the concentration of a certain compound to be measured contained in the sample is high, the amount of product ions derived from the compound is suppressed, and the detector is too large. It is possible to avoid the incidence of ions. Thereby, saturation of the signal at the detector can be prevented. On the other hand, for a compound whose concentration to be measured is originally low, the amount of product ions derived from the compound can not be suppressed, and ions derived from a trace amount of compound are efficiently incident on the detector. Therefore, a trace amount of compounds can be detected with high sensitivity.

The second aspect of the multicomponent simultaneous analysis method according to the present invention made to solve the above problems uses a tandem mass spectrometer having a mass separation unit before and after a collision cell that dissociates ions. MRM measurement is performed for each of a plurality of measurement target compounds known in the sample, and the respective compounds are quantified based on the results,
As the collision energy which is one of the measurement conditions, for a compound to be measured which has a relatively high concentration to be measured or a relatively high measurement sensitivity, the collision energy which can achieve the best dissociation efficiency for the compound to be measured Also for collision target compounds that use collision energy with low dissociation efficiency and relatively low concentration to be measured or measurement sensitivity relatively low, the collision energy that gives the best dissociation efficiency for the compound to be measured It is characterized by using.

  In a tandem mass spectrometer, changing the collision energy changes the dissociation efficiency of the ions and changes the amount of product ions reaching the detector. In the multi-component simultaneous analysis method of the second aspect, instead of intentionally selecting the MRM transition with low measurement sensitivity in the multi-component simultaneous analysis method of the first aspect, the production amount of product ions is adjusted by adjusting collision energy. cut back. The collision energy depends on the DC potential difference between the entrance end of the collision cell and the quadrupole mass filter in the previous stage or other ion optical system, so, for example, ion optics provided at the entrance end of the collision cell The collision energy can be adjusted by changing the DC bias voltage applied to the system and the preceding stage quadrupole mass filter etc.

The third aspect of the multicomponent simultaneous analysis method according to the present invention, which was made to solve the above problems, uses a mass spectrometer to perform SIM measurement or multiple SIM measurements for each of a plurality of measurement target compounds contained in the sample. A multi-component simultaneous analysis method of performing MRM measurement and quantifying each compound based on the result,
One of the measurement conditions for a measurement target compound having a relatively high measurement target concentration or a relatively high measurement sensitivity as compared to the measurement target compound having a relatively low measurement target concentration or a relatively low measurement sensitivity It is characterized in that measurement is performed with the mass resolution increased.

  For example, in a quadrupole mass spectrometer or triple quadrupole mass spectrometer, when the voltage applied to the electrodes constituting the quadrupole mass filter is adjusted to increase the mass resolution, ions that can pass through the filter can be obtained. As the mass-to-charge ratio width decreases, the amount of ions also decreases, and the signal intensity decreases. Using this phenomenon, in the multi-component simultaneous analysis method of the third aspect, detection is carried out by enhancing mass resolution instead of intentionally selecting an MRM transition with low measurement sensitivity in the multi-component simultaneous analysis method of the first aspect. Reduce the amount of ions that reach the In the triple quadrupole mass spectrometer, the mass resolution may be increased by either or both of the front quadrupole mass filter and the rear quadrupole mass filter.

The fourth aspect of the multicomponent simultaneous analysis method according to the present invention, which was made to solve the above problems, uses a mass spectrometer to perform SIM measurement or multiple SIM measurements for each of a plurality of measurement target compounds contained in the sample. A multi-component simultaneous analysis method of performing MRM measurement and quantifying each compound based on the result,
One of the measurement conditions for a measurement target compound having a relatively high measurement target concentration or a relatively high measurement sensitivity as compared to the measurement target compound having a relatively low measurement target concentration or a relatively low measurement sensitivity It is characterized by performing measurement which made the detector gain low.

  In mass spectrometers, detectors that combine conversion dynodes and electron multipliers with multistage dynodes are often used, but in such detectors, the detector gain depends on the voltage applied to the detector. Do. If the voltage applied to the detector is lowered to lower the detector gain, the detection signal becomes low because the electron multiplication effect is reduced even if the same amount of ions are incident. Using this phenomenon, in the multi-component simultaneous analysis method of the fourth aspect, the gain of the detector is lowered instead of intentionally selecting the MRM transition with low measurement sensitivity in the multi-component simultaneous analysis method of the first aspect. Lower the detection signal.

  Of course, the multi-component simultaneous analysis methods of the first to fourth aspects can be used in combination as appropriate. For example, when the reduction of the signal intensity is still insufficient even if the MRM transition is changed to one with a low measurement sensitivity by combining the first aspect and the second aspect, the collision energy is further optimized (measurement The signal strength may be further reduced by shifting from the value at which the sensitivity is maximum. By combining a plurality of methods in this manner, for example, even when a compound whose concentration to be measured is extremely high is present, it is possible to sufficiently reduce the signal intensity for such a compound to avoid signal saturation.

A mass spectrometer according to the present invention is a tandem mass spectrometer used in the multi-component simultaneous analysis method according to the first to fourth aspects,
A compound correspondence that stores the MRM transition at the time of MRM measurement and at least one of collision energy, mass resolution, and detector gain, or a parameter that determines them for each compound to be measured for all compounds to be measured. An information storage unit,
A control sequence creation unit that creates a control sequence when performing multi-component simultaneous analysis using the information stored in the compound correspondence information storage unit;
MRM transition, collision energy, mass resolution, detector gain, etc. that provide a measurement sensitivity lower than the maximum measurement sensitivity for measurement target compounds having a relatively high concentration of the measurement object or a relatively high measurement sensitivity. Alternatively, it is characterized in that any of the parameters for determining it is stored in the compound correspondence information storage unit.

  Here, the information stored in the compound correspondence information storage unit may be determined by the user who performs the measurement using the present apparatus by performing a preliminary experiment or the like, or a maker who manufactures the present apparatus It may be determined by conducting preliminary experiments etc. In the case of the residual pesticide inspection as described above, since the compounds to be measured are all determined by the positive list based on the law etc. and are common to all users, the manufacturer acquires information corresponding to a specific purpose. Can be provided to the user.

  According to the multi-component simultaneous analysis method and the mass spectrometer according to the present invention, even when the concentration to be measured is largely different or the measurement sensitivity is largely different for each compound to be measured, High sensitivity measurement can be performed on a small amount of compound while avoiding saturation. As a result, it is not necessary to group a large number of measurement target compounds into a plurality of groups and measure each as conventionally done, so it is possible to reduce the amount of sample used for measurement. Moreover, when connecting GC or LC to the front stage of a mass spectrometer, the consumption of the mobile phase used by them can also be reduced, the measurement time can be shortened, and the measurement cost can be reduced. .

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of one Example of GC-MS for enforcing the multi-component simultaneous analysis method which concerns on this invention. 3 is a flowchart showing the procedure of an operation and a process of acquiring information stored in a compound correspondence information storage unit in the GC-MS of the present embodiment. The schematic diagram of the mass chromatogram of the product ion from two compounds A and B which are the same concentration. The figure which shows the mass chromatogram by measurement of 1 ppb concentration dieldrin. The figure which shows the mass chromatogram by measurement of phenanthrene of a 200 ppb density | concentration. The figure which shows the mass chromatogram by measurement of phenanthrene of a 200 ppb density | concentration. The figure which shows the mass chromatogram by measurement of phenanthrene of a 200 ppb density | concentration. The figure which shows the mass chromatogram by measurement of phenanthrene of a 200 ppb density | concentration.

Hereinafter, one embodiment of a multi-component simultaneous analysis method and a mass spectrometer for carrying out the analysis method according to the present invention will be described in detail with reference to the attached drawings.
FIG. 1 is a schematic block diagram of one embodiment of a gas chromatograph mass spectrometer (GC-MS) including a mass spectrometer for carrying out the multi-component simultaneous analysis method according to the present invention.

  The GC-MS includes a gas chromatograph 1, a mass spectrometer 2, a data processing unit 3, a control unit 4, a voltage generation unit 5, an input unit 6, and a display unit 7. The gas chromatograph 1 comprises a sample vaporization chamber 10 for evaporating a small amount of liquid sample, a microsyringe 11 for injecting a liquid sample into the sample vaporization chamber 10, a column 13 for separating compounds in the sample in a time direction, and a column 13 And a column oven 12 for temperature control. The mass spectrometer 2 comprises an ion source 21 for ionizing a compound to be measured by an ionization method such as an electron ionization method and the like in the analysis chamber 20 which is evacuated by a vacuum pump (not shown). A quadrupole mass filter 22, a collision cell 23 internally provided with an ion guide 24 for transporting ions while focusing, and a rear quadrupole mass filter 25 having the same electrode structure as the front quadrupole mass filter 22 are incident And a detector 26 for outputting an ion intensity signal corresponding to the amount of the ions as a detection signal. The detector 26 comprises, for example, a combination of a conversion dynode and an electron multiplier.

  A detection signal from the detector 26 is converted into digital data by an analog-to-digital converter (ADC) 27 and input to the data processing unit 3. The data processing unit 3 includes a quantitative processing unit 31 and a calibration curve storage unit 32 as functional blocks, and the quantitative processing unit 31 uses the calibration curve stored in advance in the calibration curve storage unit 32 to perform a large number of measurements included in the sample. The concentrations of the target compounds are quantified respectively. The control unit 4 controls the gas chromatograph 1, the voltage generation unit 5, and the like, and the compound correspondence information storage unit 41 for multicomponent simultaneous analysis, the control sequence determination unit 42, the control sequence storage unit 43, the analysis control unit 44, and the like. Include as a functional block. In addition to the user interface through the input unit 6 and the display unit 7, the control unit 4 also performs overall control of the entire system. Under control of the control unit 4, the voltage generation unit 5 applies predetermined voltages to the ion source 21, the quadrupole mass filters 22 and 25, the ion guide 24, the detector 26 and the like in the mass spectrometer 2. .

  The data processing unit 3 and the control unit 4 each execute a dedicated control and processing software pre-installed in the computer on the computer by using a personal computer or a more advanced workstation as a hardware resource. Can be configured to realize the functions of In this case, the input unit 6 is a keyboard or pointing device (mouse or the like) attached to the computer, and the display unit 7 is a display monitor of the computer.

Next, the basic measurement operation in the GC-MS shown in FIG. 1 will be schematically described.
When a small amount of liquid sample is dropped from the microsyringe 11 into the sample vaporization chamber 10, the liquid sample is vaporized in a short time in the sample vaporization chamber 10, and various components in the sample are flowed of carrier gas such as helium. It gets on and is sent in column 13. While passing through the column 13, each substance in the sample reaches the outlet of the column 13 with a delay by different time. The column oven 12 is controlled to maintain a substantially constant temperature or to raise the temperature according to a predetermined temperature profile. In the mass spectrometer 2, the ion source 21 sequentially ionizes the compound to be measured contained in the gas supplied from the outlet of the column 13.

  According to the control sequence stored in the control sequence storage unit 43, the analysis control unit 44 applies a voltage to each rod electrode of the front stage quadrupole mass filter 22 so as to pass ions having a specific mass-to-charge ratio. Control the voltage generation unit 5. Thus, among the various ions derived from the compound to be measured introduced into the ion source 21, ions having a specific mass-to-charge ratio pass through the front quadrupole mass filter 22 and are introduced into the collision cell 23 as precursor ions. . A collision induced dissociation (CID) gas is introduced into the collision cell 23 continuously or intermittently, and precursor ions come into contact with the gas to cause cleavage to produce various product ions. The analysis control unit 44 applies a voltage that allows ions having a specific mass-to-charge ratio to pass through the voltage generation unit 5 to each rod electrode of the subsequent-stage quadrupole mass filter 25. Thereby, among the various product ions generated in the collision cell 23, ions having a specific mass-to-charge ratio pass through the rear quadrupole mass filter 25 and reach the detector 26, and detection according to the amount of the ions is performed. Data obtained by digitizing a signal is input to the data processing unit 3.

  Based on the sequentially input data (or data temporarily stored in a data storage unit (not shown)), the quantitative processing unit 31 creates a mass chromatogram in the vicinity of the time when the compound appears for each measurement target compound. Then, a peak corresponding to the compound to be measured is detected in the mass chromatogram to calculate a peak area, and reference is made to a calibration curve showing the relationship between the peak area value and the concentration stored in advance in the calibration curve storage unit 32. The concentration value, that is, the quantitative value is calculated.

Next, the operation will be described for the case of performing multi-component simultaneous analysis in which all the compounds to be measured are known using the GC-MS of this example. FIG. 2 is a flow chart showing the procedure of work and processing for acquiring information stored in the compound correspondence information storage unit in this GC-MS.
The multi-component simultaneous analysis assumed here is, for example, the inspection of pesticide residues in food according to the positive list. In that case, all the compounds to be measured are known, and for example, according to a general compound database, a combination of mass-to-charge ratio of precursor ions to be detected derived from each compound to be measured and mass-to-charge ratio of product ions Transitions, retention times under predetermined GC separation conditions, and the like are known. Therefore, if mass spectrometry apparatus 2 performs MRM measurement for a predetermined MRM transition within a predetermined measurement time range near the retention time for each measurement target compound, product ions derived from the measurement target compound can be detected without leakage. it can.

  However, in general, there are a plurality of MRM transitions corresponding to one compound, and the more complex the compound structure, the larger the number of MRM transitions. In addition, in the case of using an ion source by electron ionization, fragmentation occurs during ionization, and a plurality of types of precursor ions are generated from one compound, so the number of MRM transitions tends to increase.

  When precursor ions are dissociated to generate a plurality of product ions, their dissociation efficiencies are different from each other, resulting in differences in signal strength obtained by the MRM transition. FIG. 3 is a schematic view of mass chromatograms of product ions derived from two compounds A and B having the same concentration. In the compound A shown in FIG. 3A, at least two MRM transitions (in this example, the m / z = Ma of the precursor ion is the same but the m / z = Mb and Mc of the product ion are different) are present. The ion intensity differs greatly depending on the MRM transition. On the other hand, in the compound B shown in FIG. 3 (b), the ionic strength is lower than the maximum ionic strength for the two MRM transitions in the compound A. As described above, the compounds to be measured in the multicomponent simultaneous analysis are various, and even at the same concentration, the signal intensity of the product ion, that is, the measurement sensitivity may be largely different. Moreover, this is the case where the concentration is the same, but in multi-component simultaneous analysis for the purpose of residual pesticide inspection or contaminant inspection, the control value is largely different depending on the type of the compound to be measured. May differ greatly.

As described above, even when there is a difference in measurement sensitivity or a difference in concentration to be measured for each compound to be measured, saturation of the detection signal obtained by the detector 26 can be avoided and accurate detection is possible even for a small amount of compound. In order to be able to perform quantification, the GC-MS of the present embodiment adopts the following characteristic analysis method.
Specifically, for each compound of all measurement target compounds in multicomponent simultaneous analysis, an appropriate MRM transition and collision energy value are determined in advance, and stored in the compound correspondence information storage unit 41 for multicomponent simultaneous analysis. deep. A procedure for obtaining an appropriate MRM transition and collision energy value for each compound to be measured will be described with reference to FIG.

  Here, although a plurality of MRM transitions are known for each compound to be measured, it is unknown which MRM transition the signal strength is maximized. In that case, a standard sample containing a compound to be measured at a known concentration is directly introduced into the mass spectrometer 2 and MRM measurement is sequentially performed by sequentially setting known MRM transitions corresponding to the compound, and the signal intensity of the product ion is maximum Find the MRM transition that Next, the MRM transition is fixed to the MRM transition giving the maximum signal strength, and then the voltage generation unit 5 switches the collision energy to a plurality of stages, and the electrodes provided at the inlet of the previous stage quadrupole mass filter 22 and collision cell 23 etc. The DC bias voltage to be applied is changed, and the signal intensities of product ions under different collision energy values are determined. Then, find the collision energy value that gives the maximum signal strength. In this way, MRM transitions and collision energy values at which the signal intensity is maximized are searched for all measurement target compounds in the multicomponent simultaneous analysis (step S1). Note that software for automatic adjustment as disclosed in Non-Patent Document 1 may be used to search for such measurement conditions. If the MRM transition giving the maximum signal strength is known, the first half of step S1 may be omitted and only the collision energy value may be searched.

  The MRM transition and collision energy value obtained for each compound to be measured in step S1 are determined under the condition that the signal intensity is maximized. Therefore, next, a sample containing a compound having a concentration corresponding to the concentration range to be measured is introduced into the mass spectrometer 2 for each measurement target compound, and MRM measurement is performed under the measurement conditions obtained in step S1, Examine the signal strength of the ions. Then, the signal intensities of product ions for different measurement target compounds are compared, and for a compound whose signal intensity is too high, MRM measurement is performed by setting another MRM transition associated with the same compound, and the MRM transition Examine the signal strength under Then, for a compound having a relatively high signal strength, an MRM transition having a low signal strength is selected instead of an MRM transition having a maximum signal strength, and the MRM transition corresponding to the compound to be measured is changed (step S2).

  Subsequently, it is determined whether the suppression of the signal strength is sufficient only by the change of the MRM transition performed in the step S2 (step S3). And only the compound judged that suppression of signal strength is inadequate implements the process of step S4. That is, a sample containing a compound having a concentration corresponding to the concentration range to be measured is introduced into the mass spectrometer 2, and the collision energy value is determined from the optimum value associated with the compound (the value at which the maximum signal intensity is obtained). Perform a modified MRM measurement to increase or decrease. When the collision energy value is changed from the optimum value, the dissociation efficiency of the precursor ion in the collision cell 23 is lowered, and the signal intensity of the product ion is lowered. Therefore, the collision energy value is changed until the signal intensity decreases to a sufficient level, and the collision energy value appropriate for the compound to be measured is determined (step S4).

  Then, through the procedure of steps S1 to S4, if the appropriate MRM transition and collision energy value for all the measurement target compounds in multi-component simultaneous analysis are determined, this is stored in the compound corresponding information storage unit 41 for multi-component simultaneous analysis. For example, it stores in a table format as shown in FIG. 1 (step S5). That is, the information stored in the compound correspondence information storage unit 41 for simultaneous analysis of multiple components is appropriate considering the difference in measurement sensitivity of each compound and the difference in concentration range to be measured in simultaneous analysis of multiple components. It can be said that it is MRM transition and collision energy value. This is, of course, different from the MRM transition and collision energy values determined to maximize signal strength.

  4 to 8 are actual mass chromatograms, FIG. 4 is the actual measurement results of 1 ppb concentration of dieldrin, and FIGS. 5 to 8 are much higher concentration concentrations of 200 ppb of phenanthrene (Phenanthrene). It is an actual measurement result of FIG. 5 shows the measurement results when the collision energy is the automatically adjusted optimum value, and the vertical axis (intensity axis) of FIG. 5 is 1000 times the vertical axis of FIG. Although the concentration difference between dieldrin and phenanthrene measured is 200 times, the signal intensity difference far exceeds that, and it can also be seen that phenanthrene has higher measurement sensitivity. In order to avoid signal saturation for phenanthrene at the above concentration without reducing the signal strength for dieldrin, it is necessary to change the conditions for MRM measurement of phenanthrene.

FIG. 7 shows the results of measurement of MRM measurement by setting an MRM transition different from that shown in FIG. 5 to phenanthrene. The signal strength is reduced to 1/10 or less for the MRM transition (m / z 178.10> 176.10) in which the maximum signal strength is obtained in the MRM transition (m / z 176.10> 126.10) where the signal strength is the lowest. However, in this case, since the signal strength is still relatively high, the signal energy is lowered by further adjusting the collision energy value. FIG. 8 shows the measurement results of MRM measurement when the collision energy is increased by +30 V above the optimum value after selecting the low sensitivity MRM transition described above. The signal intensity is further reduced to 1/10 or less by the increase of the collision energy value. That is, the signal strength can be reduced to 1/100 or less by selecting an appropriate MRM transition and adjusting the collision energy value.
FIG. 6 shows the actual measurement results of MRM measurement when the MRM transition is as shown in FIG. 5 and only the collision energy value is increased by +30 V. In this case, it can be said that only the adjustment of the collision energy value is insufficient to reduce the signal strength.

  As described above, in the examples shown in FIGS. 4 to 8, the signal strength obtained under the optimum MRM transition and collision energy value by combining the selection of the low sensitivity MRM transition and the adjustment of the collision energy value. The signal strength can be sufficiently reduced as compared with. As a result, even when the concentration range to be measured is wide (in particular, the upper limit of the concentration to be measured is high), the detection signal is not saturated, and the dynamic range of the concentration to be measured can be expanded. Of course, if the concentration to be measured is not so high, it is possible to make a change to select the low sensitivity MRM transition and omit the adjustment of the collision energy value.

  When creating a control sequence (measurement method) for performing multi-component simultaneous analysis, the MRM transition stored in the storage unit 41 and information on collision energy value may be used. That is, the control sequence determination unit 42 performs MRM measurement using the MRM transition and the collision energy value stored in the storage unit 41 in the predetermined time range near the retention time in which the compound appears for each measurement target compound as measurement conditions. Create a control sequence to repeat. When the number of compounds to be measured is large, the compounds can not be sufficiently separated in the column 13 of the gas chromatograph 1, so that it is necessary to carry out MRM measurement corresponding to different target compounds in a certain time range. In that case, an MRM measurement corresponding to one measurement target compound is performed for a predetermined time, and then an MRM measurement corresponding to another measurement target compound is performed for a predetermined time, and so on. Assuming that MRM measurement corresponding to the target compound is performed one by one sequentially as one cycle, a control sequence may be created so as to obtain a temporal change in signal intensity in each target compound by repeating this cycle. .

  In addition, although acquisition of the appropriate information in the procedure shown in FIG. 2 may be performed by the user who carries out multi-component simultaneous analysis using this apparatus, it may be a residual pesticide inspection according to a positive list. If the type of the compound to be measured and the concentration range to be measured are determined regardless of the user, it is more convenient for the manufacturer of the apparatus, etc. to carry out. In such a case, in addition to storing the table format information as shown in FIG. 1 in the compound correspondence information storage unit 41 for simultaneous analysis of multiple components, such information is included as a part of control / processing software for simultaneous analysis of multiple components. Data may be provided.

  In the above embodiment, the signal intensity of the specific compound to be measured is suppressed by changing the MRM transition and further changing the collision energy value as needed. However, the collision energy is not changed without changing the MRM transition. Only the value may be changed. In addition, the signal strength may be suppressed by changing the measurement conditions other than the MRM transition and the collision energy value for each compound.

  Specifically, in the first-stage quadrupole mass filter 22, the mass-to-charge ratio of ions that can pass through the filter 22 by adjusting the high-frequency voltage and the DC voltage applied to the four rod electrodes constituting the filter 22. Control. Depending on the stability conditions of the ions in the quadrupole electric field formed in the space surrounded by the four rod electrodes, that is, by the voltage applied to each electrode, the ions of the ions (precursor ions) passing through the filter 22 Mass resolution is determined. Similarly, the voltage applied to the electrodes constituting the post-stage quadrupole mass filter 25 determines the mass resolution of ions (product ions) passing through the filter 25. When the mass resolution is increased, the width of the peak on the mass spectrum is reduced (that is, the resolution is increased), but the peak intensity is decreased. Therefore, if the applied voltage is adjusted to increase the mass resolution in either or both of the front quadrupole mass filter 22 and the rear quadrupole mass filter 25, the signal intensity of the product ions can be lowered. Therefore, it is preferable to set the mass resolution higher for a compound having high measurement sensitivity and a compound having a high concentration to be measured than the other compounds by utilizing this fact.

  Also, as described above, in general, a combination of a conversion dynode and an electron multiplier is often used as the detector 26, but the gain of such a detector 26 depends on the voltage applied to the detector 26. Do. When the gain of the detector 26 is lowered, even if the same amount of ions is incident, the detection signal is lowered. Therefore, even if a large amount of ions are incident, saturation of the detection signal can be avoided. That is, similar to the MRM transition and collision energy value described above, measurement parameters such as mass resolution and detector gain or voltage values for determining them are associated with the measurement object compound for all measurement object compounds, and the measurement sensitivity is high. Good multicomponent simultaneous analysis can be performed by storing conditions under which the signal intensity is low for the compound and the compound having a high concentration to be measured.

  In the above embodiment, the mass spectrometer 2 is a triple quadrupole mass spectrometer, but a Q-TOF mass spectrometer using a time-of-flight mass separator instead of the rear quadrupole mass filter 25 is also possible. It is clear that the invention is applicable. Also, in a single type mass spectrometer such as a quadrupole mass spectrometer rather than a tandem mass spectrometer, although the collision energy value does not exist, the mass to charge ratio of the SIM measurement target is determined instead of the MRM transition. For example, the present invention can be applied.

  Furthermore, in the above embodiment, the gas chromatograph 1 is connected to the front stage of the mass spectrometer 2, but a liquid chromatograph may be used, and the present invention may be applied even if the chromatograph is not connected. Can. That is, in a mass spectrometer using an ion source based on a so-called ambient ionization method such as a DART ion source, a plurality of measurement target compounds contained in a sample are introduced almost in time in a superimposed manner. Since the compound can be quantified from a graph showing temporal changes in signal intensity of the compound, the multicomponent simultaneous analysis method according to the present invention is useful.

  Further, since the above-described embodiment and the above-described various modifications are merely examples of the present invention, even if appropriate modifications, corrections, and additions are made within the scope of the present invention, they should be included in the claims of the present application. Is clear.

DESCRIPTION OF SYMBOLS 1 ... Gas chromatograph 10 ... Sample vaporization room 11 ... Micro syringe 12 ... Column oven 13 ... Column 2 ... Mass spectrometer 20 ... Analysis room 21 ... Ion source 22 ... Pre-stage quadrupole mass filter 23 ... Collision cell 24 ... Ion guide 25 ... latter stage quadrupole mass filter 26 ... detector 27 ... analog-to-digital converter 3 ... data processing unit 31 ... quantitative processing unit 32 ... calibration curve storage unit 4 ... control unit 41 ... compound correspondence information storage unit 42 for multi-component simultaneous analysis ... Control sequence determination unit 43 ... Control sequence storage unit 44 ... Analysis control unit 5 ... Voltage generation unit 6 ... Input unit 7 ... Display unit

Claims (6)

A multi-component method of performing SIM (selected ion monitoring) measurement or MRM (multiple reaction monitoring) measurement on each of a plurality of known measurement target compounds contained in a sample using a mass spectrometer, and quantifying each compound based on the result Simultaneous analysis method,
As a mass-to-charge ratio which is one of measurement conditions, which is a target of SIM measurement, or an MRM transition which is a target of MRM measurement, for a measurement target compound having a relatively high concentration to be measured or a relatively high measurement sensitivity, Among a plurality of mass-to-charge ratios or MRM transitions associated with the compound to be measured, the obtained signal strength uses a relatively low mass-to-charge ratio or MRM transition, and the concentration to be measured is relatively low or the measurement sensitivity Among the plurality of mass-to-charge ratios or MRM transitions associated with the to-be-measured compound, for the to-be-measured compounds having a relatively low A multi-component simultaneous analysis method using mass spectrometry characterized by A multi-component simultaneous analysis method using mass spectrometry according to claim 1, wherein the mass analysis unit using a tandem-type mass spectrometer having a mass separation unit before and after a collision cell for dissociating ions. In
As the collision energy which is one of the measurement conditions, for a compound to be measured which has a relatively high concentration to be measured or a relatively high measurement sensitivity, the collision energy which can achieve the best dissociation efficiency for the compound to be measured Also for collision target compounds that use collision energy with low dissociation efficiency and relatively low concentration to be measured or measurement sensitivity relatively low, the collision energy that gives the best dissociation efficiency for the compound to be measured A multiple component simultaneous analysis method using mass spectrometry characterized by using. MRM (multiple reaction monitoring) measurement is performed on each of a plurality of known compounds to be measured contained in the sample using a tandem mass spectrometer having a mass separation unit before and after a collision cell that dissociates ions, A multi-component simultaneous analysis method for quantifying each compound based on the result,
As the collision energy which is one of the measurement conditions, for a compound to be measured which has a relatively high concentration to be measured or a relatively high measurement sensitivity, the collision energy which can achieve the best dissociation efficiency for the compound to be measured Also for collision target compounds that use collision energy with low dissociation efficiency and relatively low concentration to be measured or measurement sensitivity relatively low, the collision energy that gives the best dissociation efficiency for the compound to be measured A multiple component simultaneous analysis method using mass spectrometry characterized by using. A multi-component method of performing SIM (selected ion monitoring) measurement or MRM (multiple reaction monitoring) measurement on each of a plurality of known measurement target compounds contained in a sample using a mass spectrometer, and quantifying each compound based on the result Simultaneous analysis method,
One of the measurement conditions for a measurement target compound having a relatively high measurement target concentration or a relatively high measurement sensitivity as compared to the measurement target compound having a relatively low measurement target concentration or a relatively low measurement sensitivity A multi-component simultaneous analysis method using mass spectrometry, which comprises performing measurement with high mass resolution. The multi-component simultaneous analysis method according to any one of claims 1 to 4, wherein
During the measurement, the measurement target concentration against the relatively high or measuring sensitivity is relatively high measurement target compound is measured concentration than the relatively low or measuring sensitivity is relatively low measurement target compound, measuring conditions multicomponent simultaneous determination method using that you lower the detector gain, which is one of mass spectrometry, characterized in. A tandem mass spectrometer used in the multi-component simultaneous analysis method according to any one of claims 1 to 5, which is a tandem mass spectrometer,
A compound correspondence that stores the MRM transition at the time of MRM measurement and at least one of collision energy, mass resolution, and detector gain, or a parameter that determines them for each compound to be measured for all compounds to be measured. An information storage unit,
A control sequence creation unit that creates a control sequence when performing multi-component simultaneous analysis using the information stored in the compound correspondence information storage unit;
MRM transition, collision energy, mass resolution, detector gain, etc. that provide a measurement sensitivity lower than the maximum measurement sensitivity for measurement target compounds having a relatively high concentration of the measurement object or a relatively high measurement sensitivity. Alternatively, any one of the parameters for determining it is stored in the compound correspondence information storage unit.

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