JP2001050944A - Gas chromatograph direct-connected mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas chromatograph direct-connected mass spectrometer for improving reliability and measurement efficiency. SOLUTION: When power is turned on, an adjustment is automatically started, a filament is turned on (12), and an electronic base line check is executed (14). Analysis conditions for adjustment being stored are read (16), and a standard sample gas for adjustment is introduced to an ion trap in the mass spectrometer (18). By using the base peak of the standard sample gas, sensitivity is adjusted (20). The correction of a mass marker is executed so as to match with the mass of a registered standard peak (22). It is checked whether no water exists within the device exceeding a specific value, no air is leaked, no background peak exceeding a preset value exists, and the mass spectrum of a standard substance matches with a determined pattern within the range of an error (24). The introduction of the standard sample gas is stopped (26), and adjustment result is displayed and simultaneously stored (28). The presence or the absence of the error is checked (30), a guidance is displayed (32) according to the type of error (32), and measurement is started if no errors exist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph direct mass spectrometer, and more particularly to a gas chromatograph direct 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 mass spectrometer, a sample component to be measured separated by a gas chromatograph is led to a mass spectrometer to generate ions, and the ions are subjected to mass analysis to obtain a mass spectrum. For ion generation, the EI method in which electrons collide 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 that a sample is charged by an ESI method or an atmospheric pressure chemical ionization method / APCI method which chemically ionizes the sample. Further, as a mass spectrometer, a magnetic field type mass spectrometer, a quadrupole type mass spectrometer, a three-dimensional quadrupole type mass spectrometer, and the like are known.

[0003]

Since a mass spectrometer is a device for introducing a sample to be measured into the device and performing destructive analysis, contamination inside the device cannot be avoided with the analysis. Most of the generated ions are discharged out of the device by the exhaust device, but a part of the ions adhere to the inside of the device. When the amount of contaminants adhered exceeds a certain limit, the sensitivity is reduced and the pattern of the mass spectrum is changed, the measurement accuracy is significantly reduced, 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. Insufficient sample pretreatment may cause the sample to contain moisture, cause air leaks from the sample inlet of the gas chromatograph, or cause sample-derived contaminants to adhere to the inlet or separation column. Or
Seriously affects measurement accuracy. Therefore, it is indispensable to check the state of the apparatus, make adjustments, and if necessary, take measures such as cleaning of the apparatus before starting the measurement, in order to obtain reliable measurement results. However, these operations are not always executed because they are left to the arbitrariness of the operator. Even if executed, the adjustment may require some skill, so that an appropriate result may not be obtained.

[0004] It is an object of the present invention to provide a gas chromatograph direct mass spectrometer suitable for improving the reliability of measurement results and improving the analysis efficiency.

[0005]

A feature of the present invention is that a gas chromatograph including a separation column for separating a sample to be measured injected from a sample inlet into components is provided. Mass spectrometer for generating ions and performing mass spectrometry on the generated ions; and means for automatically executing 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 includes a moisture content check and an air content check.

[0006] Other objects and features of the present invention will become apparent from the following description made with reference to the drawings.

[0007]

FIG. 2 shows an outline of a gas chromatograph-direct mass spectrometer showing one embodiment according to the present invention. The sample to be measured injected from the sample inlet 1 of the gas chromatograph is separated into components by a separation column 2 of the gas chromatograph, and the separated components are introduced into a mass spectrometer 3 which is exhausted by a vacuum pump. Two end cap electrodes 4 and 5 and a donut-shaped ring electrode 6 are arranged in the mass spectrometer 3, and a gas component flowing out of the gas chromatograph is introduced into an ion trap portion which is a space surrounded by the electrodes. Is done.

[0008] Thermions emitted from the filament 7 are
Through the hole formed in the end cap 4, it collides with the introduced sample molecule to be measured, and its ions are generated. The generated ions are 1 MHz applied to the ring electrode 6.
It is stably captured by the high frequency. After accumulating ions while keeping the high frequency constant for a certain period of time, by changing the voltage (amplitude) of the high frequency, the accumulated ions are emitted from a hole formed in the center of the end cap electrode 5. The emitted ions are detected by a detector 8, and the detected signal is input to a control and data processing device 9,
A mass spectrum is obtained.

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

Note that the voltages of the end cap electrodes 4 and 5 and the ring electrode 6, the voltage of the detector 8, the filament 7
Is controlled 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 mass spectrometer based on the present invention.
This processing 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 automatically starts, A current is applied to the filament 7 to light it (step 12), and the tuning 1 required to determine the peak when measuring the sample to be measured is determined.
A seed electronic baseline check is performed (step 14, subroutine A). The term electronic baseline 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 calibration standard sample gas introduced into the mass spectrometer 3. Used.

FIG. 3 shows a flowchart of an electronic baseline check subroutine. First, in order to initialize the error flag, a code of Nothing is assigned to the error flag (step 100). A / D conversion is performed on the signal from the detector 8 at intervals of 10 ms, and data of 10 points is integrated to obtain data of one point (step 102). This one
Repeat 100 times to obtain 100 points of data. In order to remove the influence of noise on the data, data of five points from the larger one and data of five points from the smaller one are removed (step 104). The data of the remaining 90 points are integrated, an average value is obtained, and the average value is substituted into Base (step 106).

It is confirmed that this Base is larger than 0 (step 108), and if it is smaller, an error code Base0Er is set to Err.
Substitute for Flag (step 110). Next, it is confirmed that Base is smaller than a predetermined maximum value Bmax of the baseline (step 112).
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 analysis conditions for adjustment stored in the control and data processing device 9 are read (step 16). The electromagnetic valve 11 connecting 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 flowchart of the sensitivity adjustment subroutine. First, it is confirmed that ErrFlag is Nothing and no error has been detected first (step 12).
0) If the error has occurred first, the process is terminated. No
If it is a thing, the high voltage power supply of the detector 8 is turned on and waits for 10 seconds until the power supply is stabilized (step 122).
The high voltage of the multiplier as the detector 8, which is the analysis condition for adjustment, is read from the control and data processing device 9,
HV (step 124), and a voltage of MHV is applied to the multiplier (step 126).

The high frequency voltage of the ring electrode 6 is scanned to acquire a mass spectrum and obtain the maximum peak intensity (step 128). Strength is constant strength DefInt
Check if greater than (step 130)
If smaller, 1 is added to the MHV (step 132). It is checked whether MHV is smaller than a predetermined maximum voltage MaxMHV (step 134). If it is larger, MultiER is substituted for ErrFlag, and the process ends (step 136). If the intensity is larger than DefInt in step 130, the MHV is written to 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 a kind 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 mass marker correction subroutine. First, it is confirmed that ErrFlag is Nothing and no error has been detected first (step 140), and if an error has occurred first, the process is terminated. If Nothing, control the list of standard peak (usually multiple) masses registered and data processing device
Read from step 9 and register the mass of the registered standard peak to StM
Substitute into Z (step 142). Start search range of StMZ ± 1.0 (meaning that the search range is within ± 1 unit)
rtMZ, and the end value is EndMZ (step 144).

Within the range from StartMZ to EndMZ, a peak having the maximum intensity is searched for, its mass is ObsMZ, and its intensity is ObsInt.
(Step 146). It is confirmed that a peak exists in the search range and ObsInt is larger than a predetermined intensity IDef (step 148).
Substitute into rFlag (step 150). ObsInt from Idef
Is larger, the 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 finished, return to step 142 to read the next standard peak.

If it is the end, the process ends.

Returning to FIG. 1, the moisture in the apparatus does not exist above a 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 the pattern matches the error within the range of the error (step 24, subroutine D).

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

The intensity of the water peak m / z 18 is determined, and it is confirmed that this intensity is 1% or less of BaseInt (step 164). In some cases, the sample to be measured to be separated by gas chromatography and subjected to mass analysis in the mass spectrometry unit 3 is insufficiently pretreated.
When the water is too much OH ^- are generated, which are combined with sample molecules, it is not obtained the 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 ends (step 166).

If it is less than 1%, 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 less than 1% of BaseInt (step 168). If the sample injection hole of the septum set at the sample injection port 1 of the gas chromatograph becomes large due to long-term use, or if the connection portion is deteriorated due to a change in column temperature, air leakage occurs, and this causes the mass spectrometry The ionization efficiency of the sample to be measured in 3 is reduced, thereby reducing the sensitivity. 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, a background peak check and a standard substance pattern check are performed. Look for the peak and see 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 it is confirmed that the intensity is 1% or less of BaseInt (step 174). If it is 1% or more, it is determined that the background is too much, so BGrEr is substituted for ErrFlag, and the process ends (step 176). If it is 1% or less, it is determined that there is no problem, and the next peak is read.

In some cases, contaminants accompanying the sample injection are mixed into the sample injection port or the separation column of the gas chromatograph and flow into the mass spectrometer 3. In this case, the contaminants give a background peak. In addition, a sample, a decomposition product of the sample,
Chemical reaction products of the samples may adhere to each other, and in this case, the attached substances give a background peak.
Background peaks hinder correct mass spectrum acquisition. Steps 172 and 174 can perform such a background check.

If it is a standard peak in step 172, it is checked whether the ratio of the intensity to BaseInt is equal to the ratio of the peak registered in the control and data processing device 9 within an allowable range (step 172). 178). If it is out of the allowable range, it is a mass spectrum pattern failure, so STDrEr is substituted for ErrFlag, and the process ends (step 180). If so, check if the check in step 178 was performed on the last peak of all the standard peaks (step 182);
Returning to step 2, the next peak is confirmed, and if so, the process ends.

When the ion trap portion serving as an ion source is contaminated, the contaminant acts as a catalyst, changing the fragment mass spectro pattern, changing the ionization efficiency, and shifting the equilibrium point of the ion interaction. Therefore, the mass spectrum pattern changes. Therefore, it can be said that step 178 is a step for 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 result of the adjustment is displayed on the display device (CRT) of the control and data processing device 9 and is simultaneously saved on the hard disk (step 2).
8).

It is checked whether ErrFlag is Nothing (step 30). If not, 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 for it.
In the figure, an amplifier is a detection system amplifier including a detector 8, a high-frequency voltage is a power supply of a high-frequency voltage applied to the end cap electrodes 4 and 5, an injector is a sample injection port 1,
The septum means an elastic body such as a rubber into which a sample injection needle set in the sample injection port 1 is inserted.

FIG. 8 shows an example of a format of a storage file of the adjustment result stored in the control and data processing device 9. The file contains the date and time the adjustment was made, if there was an error, the content of the error in the Error column, the electronic baseline in the EBAse column, the detector voltage in the Multi column for the intensity of the base peak, and the intensity of the base peak in the BaseInt column. ,
The mass before correction 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. A graph connected by diamond dots indicates a water trend graph, and a graph connected by rectangular dots indicates a nitrogen trend graph.

If No in step 30, 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 results are added and output as an adjustment report when the measurement results are output and displayed. The upper half of the data of the “M-7100 GC / 3DQMS System Manager Quantitative Report” is substantially the same as the normally displayed data, and the upper and lower data in the upper and lower data are the control and data processing devices 9 respectively. 1 shows chromatograms and mass spectra processed by.
The lower half of the data, "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 numeral in the mass marker adjustment report indicates a measured value, and the lower numeral indicates a theoretical value.

As described above, since the adjustment of the apparatus is always performed under the same conditions without depending on the operator, the reliability of the measurement result can be improved, and the operator can immediately start the analysis. Can improve the analysis efficiency.

Also, by attaching the adjustment result to the analysis result, the reliability of the analysis result can be guaranteed. Since the stored adjustment result is automatically left as a log file, it is possible to easily track the secular change of 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 direct mass spectrometer.

If there is an abnormality during the execution of the adjustment,
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 direct mass spectrometer capable of improving reliability and measurement efficiency.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of the entire apparatus showing an outline of a gas chromatograph direct mass spectrometer showing one embodiment according to the present invention.

FIG. 3 is a view showing a flowchart of an electronic baseline check subroutine in FIG. 1;

FIG. 4 is a view showing a flowchart of a sensitivity adjustment subroutine in FIG. 1;

FIG. 5 is a view showing a flowchart of a subroutine for correcting a mass marker in FIG. 1;

FIG. 6 is a view showing a flowchart of a spectrum pattern check subroutine in FIG. 1;

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

FIG. 8 is a view showing an example of a format of an adjustment result storage file stored in the control and data processing apparatus of FIG. 1;

9 is a diagram showing an example of a trend graph created by extracting the relative intensities of the water peak and the air peak from the adjustment results stored in the control and data processing device of FIG. 1;

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

[Explanation of symbols]

1: sample inlet, 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: reservoir of standard sample gas for adjustment, 11: solenoid valve.

Claims (6)

[Claims] 1. A gas chromatograph including a separation column for separating a sample to be measured injected from a sample injection port for each component, and generating ions of separated components flowing out of the separation column and generating the generated ions. A mass spectrometer for mass spectrometry, and means for automatically executing tuning and a spectrum pattern check based on a mass spectrum of an adjustment standard sample prior to the measurement of the sample to be measured, wherein the spectrum pattern check includes a water content A mass spectrometer directly connected to a gas chromatograph, which includes a check of the amount of air and a check of the amount of air. 2. The mass spectrometer of claim 1, wherein the tuning includes an electronic baseline check, sensitivity adjustment, and mass marker correction. 3. The mass spectrometer directly connected to a gas chromatograph according to claim 2, further comprising means for storing data representing the results of the tuning and the spectrum pattern check. 4. A mass spectrometer directly connected to a gas chromatograph according to claim 3, wherein said stored data is attached to data representing a measurement result of said sample to be measured and outputted. 5. A mass spectrometer directly connected to a gas chromatograph according to claim 3, wherein said stored data is output as a long-term trend graph. 6. A mass directly connected to a gas chromatograph according to claim 2, wherein when an abnormality is detected as a result of said tuning and pattern check, the abnormality content and the content to be taken are displayed. Analysis equipment.