JP3452845B2 - Gas chromatograph direct mass spectrometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph directly coupled mass spectrometer, and more particularly to a gas chromatograph directly coupled mass spectrometer having means for performing tuning and pattern check prior to measurement of a sample to be measured.

[0002]

2. Description of the Related Art In a gas chromatograph direct-attached mass spectrometer, a sample component to be measured separated by a gas chromatograph is guided to a mass spectrometer to generate its ions, and the ions are subjected to mass spectrometry to obtain a mass spectrum. Regarding ion generation, the EI method in which electrons are collided with the sample to be measured, the electrospray method in which the sample to be measured is sprayed under a high voltage /
It is known to apply a charge to the sample by the ESI method or the atmospheric pressure chemical ionization method / APCI method of chemically ionizing the sample. Known mass spectrometers include a magnetic field mass spectrometer, a quadrupole mass spectrometer, and a three-dimensional quadrupole mass spectrometer.

[0003]

Since the mass spectrometer is a device for introducing a sample to be measured into the device for destructive analysis, the inside of the device is unavoidably contaminated with the analysis. Most of the generated ions are discharged to the outside of the device by the exhaust device, but some of them are attached to the inside of the device. When the adhered contaminant exceeds a certain limit, the sensitivity is lowered and the pattern of the mass spectrum is changed, the measurement accuracy is remarkably lowered, and the analysis result becomes unreliable. Further, a detector such as a multiplier gradually deteriorates due to a change with time, and the sensitivity decreases. In addition, the sample pretreatment is insufficient and the sample becomes moist, air leaks from the sample inlet of the gas chromatograph, and contaminants derived from the sample adhere to the inlet and separation column. Or
The measurement accuracy is seriously affected. Therefore, in order to obtain a reliable measurement result, it is indispensable to check the state of the device, make adjustments, and perform measures such as cleaning of the device before starting the measurement. However, these operations are not always executed because they are left to the discretion of the operator. Even if it is executed, it may not be possible to obtain an appropriate result because adjustment requires some skill.

An object of the present invention is to provide a gas chromatograph directly coupled mass spectrometer suitable for improving the reliability of measurement results and improving the analysis efficiency.

[0005]

The features of the present invention are that a gas chromatograph including a separation column that separates a sample to be measured injected from a sample injection port into each component, and a separated component that flows out from the separation column. A mass spectrometer for generating ions and performing mass spectrometry on the generated ions, and means for automatically performing tuning and spectrum pattern check based on the mass spectrum of the adjustment standard sample prior to the measurement of the sample to be measured. And the spectral pattern check includes a water content check and an air content check.

Other objects and features of the present invention will become apparent from the following description made with reference to the drawings.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows an outline of a gas chromatograph direct coupling mass spectrometer showing an embodiment based on the present invention. The sample to be measured injected from the sample inlet 1 of the gas chromatograph is separated into each component by the separation column 2 of the gas chromatograph, and the separated components are introduced into the mass spectrometer 3 exhausted by the vacuum pump. In the mass spectrometer 3, two end cap electrodes 4 and 5 and a donut-shaped ring electrode 6 are arranged, and the outflow gas component from the gas chromatograph is introduced into an ion trap part which is a space surrounded by those electrodes. To be done.

The thermoelectrons emitted from the filament 7 are
The ions are generated by colliding with the introduced sample molecules to be measured through the holes formed in the end cap 4. The generated ions are 1 MHz applied to the ring electrode 6.
It is stably captured at a high frequency. After accumulating ions by keeping the high frequency constant for a certain period of time and then changing the voltage (amplitude) of the high frequency, the accumulated ions are ejected from the hole formed in the center of the end cap electrode 5. The ejected ions are detected by the detector 8, and the detected signal is input to the control and data processing device 9,
A mass spectrum is obtained.

A reservoir 10 containing a standard sample gas containing a standard substance for device adjustment is connected to the mass spectrometric section 3. Therefore, when the solenoid valve 11 is opened, the reservoir 1
The standard sample gas for adjustment within 0 is introduced into the ion trap portion, diffused by the high vacuum, and ionized in the same manner as the sample to be measured to obtain a mass spectrum. At this time,
The introduction of the sample to be measured from the separation column 2 into the ion trap section is blocked.

The voltage of the end cap electrodes 4 and 5 and the ring electrode 6, the voltage of the detector 8, the filament 7
The current supply control is performed by the control and data processing device 9. The opening and closing of the solenoid valve 11 is also controlled by the control and data processing device 9.

FIG. 1 shows a flow of a reliability verification process of a gas chromatograph direct connection mass spectrometer according to the present invention.
This process is performed using a standard sample gas for adjustment prior to measurement or analysis of the sample to be measured, and when the power of the control and data processing device 9 is turned on by the operator, the adjustment starts automatically, An electric current is passed through the filament 7 to turn it on (step 12), which is one of the tunings necessary for determining the peak when measuring the sample to be measured.
A seed electronic baseline check is performed (step 14, subroutine A). The electronic baseline name is used when the introduction of the sample to be measured from the gas chromatograph to the mass spectrometer 3 is stopped and the baseline is checked with the adjustment standard sample gas introduced to the mass spectrometer 3. Used.

FIG. 3 shows a flow chart of the electronic baseline check subroutine. First, in order to initialize the error flag, the code Nothing is assigned to the error flag (step 100). The signal from the detector 8 is A / D converted at 10 ms intervals, and the data of 10 points are integrated to obtain 1 point of data (step 102). This one
Repeat 100 times to obtain 100 points of data. In order to remove the influence of noise on the data, the data of 5 points from the largest and the data of 5 points from the smallest are excluded (step 104). The remaining 90 points of data are integrated to obtain an average value, which is substituted into Base (step 106).

It is confirmed that this Base is larger than 0 (step 108), and if it is smaller, the error code Base0Er is set to Err.
Substitute in Flag (step 110). Next, it is confirmed that Base is smaller than the specified maximum value Bmax of the baseline (step 112), and if it is larger, the error code BaseHE
Substitute r for ErrFlag (step 114). If the confirmation result is good, Base is recorded (stored) in the control and data processing device 9 as an electronic baseline and set (step 116).

Returning to FIG. 1, the analytical conditions for adjustment stored in the control and data processing unit 9 are read (step 16). The electromagnetic valve 11 that connects the reservoir 10 containing the standard sample gas for adjustment and the mass spectrometer 3 is opened, and the standard sample gas for adjustment is introduced into the ion trap section in the mass spectrometer 3 (step 18). Sensitivity adjustment, which is a kind of tuning, is performed using the base peak of the standard sample gas for adjustment (step 20, subroutine B).

FIG. 4 shows a flow chart of the sensitivity adjustment subroutine. First, make sure that ErrFlag is Nothing and no error was detected first (step 12
0), if an error has occurred earlier, the process ends. No
If it is thing, the high-voltage power supply of the detector 8 is turned on, and waits for 10 seconds until the power supply becomes stable (step 122).
The high voltage of the multiplier as the detector 8 which is the analytical condition for adjustment is read from the control and data processing device 9 and M
The voltage is set to HV (step 124), and the MHV voltage is applied to the multiplier (step 126).

The high frequency voltage of the ring electrode 6 is scanned to capture the mass spectrum and obtain the maximum peak intensity (step 128). Strength is constant strength DefInt
Check if greater than (step 130),
If it is smaller, 1 is added to MHV (step 132). It is checked whether or not MHV is lower than the defined maximum voltage MaxMHV (step 134), and if it is smaller, the process returns to step 126. If it is larger, MultiER is assigned to ErrFlag, and the process is terminated (step 136). If the intensity is larger than DefInt in step 130, MHV is written in the control and data processing device 9 as the analysis condition for adjustment (step 1
38).

Returning to FIG. 1, mass marker correction, which is one type of tuning, is executed so as to match the mass of the registered standard peak (step 22, subroutine C).

FIG. 5 shows a flowchart of a subroutine for correcting the mass marker. First, it is confirmed that ErrFlag is Nothing and that no error has been detected first (step 140). If an error has occurred first, the process ends. If Nothing, control and data processing equipment for a list in which the masses of standard peaks (usually multiple) are registered.
Read the data from 9 and read the registered standard peak mass to StM.
Substitute for Z (step 142). Start the search range opening price of StMZ ± 1.0 (meaning that the search range is within ± 1 mass unit) to Sta
Let rtMZ and the final price be EndMZ (step 144).

In the range from StartMZ to EndMZ, the peak with the highest intensity is searched for, its mass is ObsMZ, and its intensity is ObsInt.
(Step 146). Confirm that there is a peak in the search range and that ObsInt is larger than the specified intensity IDef (step 148). If it is smaller, CorrectErr is set to Er.
Substitute in rFlag (step 150). ObsInt from Idef
If is larger, ObsMZ is registered in the correction table in the control and data processing device 9 (step 152). Check if the standard peak is over (step 15
4) If not, return to step 142 to read the next standard peak.

If it is finished, the process is terminated.

Returning to FIG. 1, the water content in the apparatus is not above the predetermined value, there is no air leakage, there is no background peak above the predetermined value, and the mass spectrum of the standard substance is defined. It is checked that they match with each other within the error range (step 24, subroutine D).

FIG. 6 shows a flowchart of the spectrum pattern check subroutine. Spectral pattern check is to check whether correct results are obtained when the sample to be measured is subjected to measurement or analysis.First, confirm that ErrFlag is Nothing and that no error is detected first ( In step 160), if an error has occurred earlier, the process ends. If Nothing,
M / z6 showing the maximum intensity in the mass spectrum of the standard substance
Calculate the intensity of the 9th peak and set it as BaseInt (Step 1
62).

The intensity of the m / z 18 peak, which is the peak of water, is determined, and it is confirmed that this intensity is 1% or less of BaseInt (step 164). There is a case where the sample to be measured which has been separated by the gas chromatograph and to be subjected to the mass analysis in the mass spectrometric section 3 contains insufficient water due to insufficient pretreatment.
If there is too much water, OH ^- is generated, and this binds to the sample molecules, making it impossible to obtain a correct mass spectrum. Therefore, when the water content is 1% or more, it is determined that the water content is too much, WaterEr is substituted for ErrFlag, and the process is terminated (step 166).

If it is 1% or less, the intensity of the peak of m / z 28, which is the peak of nitrogen gas in the air, is obtained, and it is confirmed that this intensity is 1% or less of BaseInt (step 168). An air leak occurs due to the sample injection hole of the septum set in the sample injection port 1 of the gas chromatograph becoming large due to long-term use, or the connection part thereof being deteriorated due to a change in the column temperature. The ionization efficiency of the sample to be measured in 3 is reduced, and thereby the sensitivity is reduced. Therefore, when the nitrogen peak intensity indicating the amount of air is 1% or more, it is determined that air leakage has occurred, AirEr is substituted for ErrFlag, and the process is terminated (step 170).

When the nitrogen peak intensity is 1% or less, the background peak and the standard substance pattern are checked. Look for the peak and check if the mass matches the mass of the standard peak (step 17
2) If they do not match, it is regarded as a background peak, and the intensity is confirmed to be 1% or less of BaseInt (step 174). When it is 1% or more, it is determined that the background is too much, so BGrEr is substituted into ErrFlag, and the process is terminated (step 176). If it is 1% or less, it is determined that there is no problem and the next peak is read.

There is a case where a pollutant accompanying the sample injection is mixed in the sample inlet or the separation column of the gas chromatograph and flows into the mass spectrometric section 3. In this case, the pollutant gives a background peak. In addition, the sample on the inner surface of the ion trap, which is the ion source, and the decomposed product
The chemical reaction products of the samples may adhere to each other, and in this case, the adhered substances also give a background peak.
Background peaks hinder the acquisition of correct mass spectra. Steps 172 and 174 can perform such a background check.

If the peak is a standard peak in step 172, it is confirmed whether the ratio of the intensity and BaseInt is equal to the ratio of the peak registered in the control and data processing device 9 within an allowable range (step). 178). If it is out of the allowable range, the mass spectrum pattern is defective, so STDrEr is substituted into ErrFlag, and the process is terminated (step 180). If it is within the allowable range, it is confirmed whether the check in step 178 is performed for the last peak of all the standard peaks (step 182), and if not, in step 17
Returning to step 2, the next peak is confirmed, but if so, the process ends.

When the ion trap, which is the ion source, is contaminated, the pollutant acts as a catalyst to change the fragment mass spectroscopic pattern, change the ionization efficiency, and shift the equilibrium point of ionic interactions. Therefore, the mass spectrum pattern changes. Therefore, it can be said that step 178 is a step of checking whether the mass spectrum pattern of the standard substance is correct.

Returning to FIG. 1, the standard sample gas introduction valve 11 for adjustment is closed (step 26). The adjustment result is displayed on the display device (CRT) of the control and data processing device 9 and simultaneously stored in the hard disk (step 2).
8).

It is confirmed whether or not ErrFlag is Nothing (step 30). If it is not Nothing, guidance for the operator is displayed according to the type of error (step 32).

FIG. 7 shows a display example of a guidance message indicating the type of error and the content to be taken.
In the figure, an amplifier is a detection system amplifier including a detector 8, a high frequency voltage is a power source of a high frequency voltage applied to the end cap electrodes 4 and 5, and an injector is a sample inlet 1.
The septum means an elastic body such as rubber into which the sample injection needle set in the sample injection port 1 is inserted.

FIG. 8 shows an example of the format of a file for saving the adjustment results saved in the control and data processing device 9. The file contains the date and time the adjustment was made, the contents of any errors in the Error column, the electronic baseline in the EBAse column, the base peak intensity in the Multi column and the detector voltage, and the Base Int column in the base peak intensity. ,
The uncorrected mass of each standard peak and the relative intensity% with respect to the base peak are stored.

FIG. 9 shows an example in which the relative intensities of the water peak and the air peak are extracted from the stored adjustment results to create a long-term trend graph. Graphs connected by diamond dots show water trend graphs, and graphs connected by rectangular dots show nitrogen trend graphs.

If the result in step 30 is Nothing, the adjustment has been completed normally, and the measurement of the sample to be measured is started (step 34). After the measurement is completed, the adjustment result is displayed together with the measurement result (step 36).

FIG. 10 shows an example in which the stored adjustment result is added and output as an adjustment report when the measurement result is output. The upper half data of the "M-7100 GC / 3DQMS System Manager Quantitative Report" is substantially the same as the data that is normally displayed, and the upper and lower data in it are the control and data processing unit 9 respectively. 3 shows the chromatogram and mass spectrum processed by.
The lower half of the data called the "adjustment report" is the data that is output in addition to those data. The upper table shows the mass marker adjustment report, and the lower data shows the intensity ratio of each mass number substance to the base intensity. . The upper numbers in the mass marker adjustment report indicate measured values, and the lower numbers indicate theoretical values.

As described above, since the adjustment of the device is always performed under the same condition regardless of the measurer, the reliability of the measurement result can be improved and the measurer must immediately take the analysis. Therefore, the analysis efficiency can be improved.

Further, by attaching the adjustment result to the analysis result, the reliability of the analysis result can be guaranteed. Since the saved adjustment result is automatically left as a log file, it is possible to easily track secular changes in the device state at a later date. This is a particularly useful function for an apparatus that requires periodic overhaul, such as a gas chromatograph directly coupled mass spectrometer.

If there is an abnormality during the adjustment execution,
In order to estimate the cause and instruct the operator to respond,
Maintainability is improved.

[0039]

According to the present invention, there is provided a gas chromatograph directly coupled mass spectrometer which can improve reliability and measurement efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a flow of a reliability verification process of a gas chromatograph directly connected mass spectrometer according to the present invention.

FIG. 2 is a configuration diagram of the entire apparatus showing an outline of a gas chromatograph directly coupled mass spectrometer showing one embodiment based on the present invention.

3 is a diagram showing a flowchart of an electronic baseline check subroutine in FIG.

FIG. 4 is a diagram showing a flowchart of a sensitivity adjustment subroutine in FIG.

5 is a diagram showing a flowchart of a correction subroutine of the mass marker in FIG.

FIG. 6 is a diagram showing a flowchart of a spectrum pattern check subroutine in FIG.

FIG. 7 is a diagram showing a display example of an error type according to the present invention and a guidance message corresponding thereto.

8 is a diagram showing an example of a format of a file for saving adjustment results saved in the control and data processing device of FIG.

9 is a diagram showing an example of a trend graph created by extracting relative intensities of a water peak and an air peak from the adjustment results stored in the control and data processing device of FIG.

FIG. 10 is a diagram showing an example in which the adjustment result stored in the control and data processing device is added and output as an adjustment report and displayed when the measurement result is output.

[Explanation of symbols]

1: sample injection port, 2: separation column, 3: mass spectrometer,
4, 5: end cap electrode, 6: ring electrode, 7: filament, 8: detector, 9: control and data processing, 1
0: standard sample gas reservoir for adjustment, 11: solenoid valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 30/72 G01N 27/62

Claims (4)

(57) [Claims] 1. A gas chromatograph including a separation column that separates a sample to be measured injected from a sample injection port into each component, and ions of the separated components that flow out from the separation column to generate the generated ions. A mass spectrometer for mass spectrometry, and means for automatically performing tuning and spectral pattern check based on the mass spectrum of the adjustment standard sample prior to the measurement of the sample to be measured, wherein the spectral pattern check is the water content. And a check of the amount of air, and means for saving the data representing the results of the tuning and the spectral pattern check, and the saved data is output as a long-term trend graph. Tograph directly connected mass spectrometer. 2. The gas chromatograph directly coupled mass spectrometer according to claim 1, wherein the tuning includes electronic baseline check, sensitivity adjustment and mass marker correction. 3. The mass spectrometer directly connected to a gas chromatograph according to claim 1, wherein the stored data is attached to data representing the measurement result of the sample to be measured and output. 4. The mass directly connected to a gas chromatograph according to claim 1, wherein when an abnormality is detected as a result of the tuning and pattern check, the abnormality content and the content to be taken for it are displayed. Analysis equipment.