JPS60207051A - Chromatographic mass spectrometer - Google Patents

Abstract

PURPOSE:To efficiently use memory capacity for storing ion detection output data, by changing the mass scanning cycle of a mass spectrometer corresponding to the peak width of the specimen component separated by a chromatograph. CONSTITUTION:A computer 9 samples the outputs of a total ion detector 5 at a constant cycle and obtains the differentiation signal of a chromatogram of the basis of the difference between adjacent sampling data. When this differentiation signal exceeds a predetermined value, a signal is sent to an interface 2 and a specimen is introduced into a mass spectrometer to perform mass scanning. The cycle of mass scanning to the first peak of the chromatogram is set to the computer 9 and a power source circuit 10 is controlled on the basis of this cycle to the first peak. The computer 9 counts a time from the start of mass scanning to the finish thereof and properly selects said time to discard the lower rank figure of the value obtained by dividing said time by a set ineger and the cycle of mass scanning in the next time peak is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a chromatographic mass spectrometry needle suitable for performing mass fragmentography.

・Conventional technologyMass fragmentography is a method in which several types of fragment ions (fragment ions) are generated when sample molecules are ionized using an electron impact method. The mass spectrometer selects and detects several types of ions, and the sample components separated by the chromatograph are introduced into the mass spectrometer, and the increase and decrease of each ion over time is recorded. It becomes possible to identify separated sample components and to discriminate components that are insufficiently separated by chromatography.

When performing mass fragmentography, a mass spectrometer switches the ion acceleration voltage according to the mass of the ion to be detected, repeats discrete mass scans, and records the detected intensity of each ion.

At this time, the period of mass scanning must be selected so that several scans are performed within the width of one peak of the sample component on the chromatograph.

However, when a capillary column is used in a chromatograph, the peaks of the sample components that appear at the beginning are very narrow and sharp, but the peak width gradually becomes wider as the time progresses. In such cases, the mass scanning period of the mass spectrometer is set short to match the sharp peak that appears at the beginning, so one peak is When the number of mass scans in a system increases significantly, and the ion detection output data is stored in memory for later data analysis, the required memory capacity increases.
This was a waste of memory capacity.

C. OBJECTIVES The present invention aims to suppress unnecessary increases in memory capacity required for performing mass fragmentography, and to enable efficient use of memory capacity.

2. Structure The present invention automatically changes the mass scanning period of the mass spectrometer according to the width of sample component peaks separated by chromatography, and reduces the number of mass scans for one peak, whether it is a sharp peak or a broad peak. Provided is a chromatograph mass spectrometer that is made to be the same.

E. Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. 1 is a gas chromatograph, 2 is an interface such as a molecular separator that connects the gas chromatograph and a mass spectrometer, 3 is an ion source, 4 is an ion accelerating electrode, 5 is a total ion detector, 6
7 is a magnetic field for mass spectrometry, 7 is an ion detector, and 8 is a memory for storing detected ion intensity data. Reference numeral 9 represents a computer controlling the entire apparatus, and reference numeral 10 represents a power supply circuit generating an ion accelerating voltage. The ion accelerating voltage power supply circuit IO generates a stepped voltage as shown in FIG. 2 and applies it to the ion accelerating electrode 4. T in FIG. T is controlled. FIG. 3 is an example of a chromatogram, which is a record of the output of the total ion detector 5. The computer 9 samples the output of the total ion detector 5 at regular intervals.
The differential signal of the chromatogram is obtained by the difference between adjacent sampling data. Of course, any method can be used to obtain this differential signal. When the differential signal exceeds a predetermined value, the computer sends a signal to the interface 2 to be introduced into the mass spectrometer, starts operation of the power supply 10 to perform mass scanning, and stores the output of the ion detector 7 in the memory 8. Make me remember. Then, the mass scanning and detection output memory stops when the output of the total ion detector 5 falls below the set level, and sends a signal to the interface 2 to stop the introduction of sample components into the mass spectrometer. Finish the operation for one peak in the chromatogram.

A mass scanning period for the first peak of the chromatogram is set in the computer 9, and the computer 9 uses this period to set the mass scanning period to the power supply circuit 10 for the first peak.
is controlled. On the other hand, the computer 9 counts the time from the start to the end of the mass scan, selects and sets the time appropriately, divides it by a certain integer, and cuts off the lower digits of the obtained value\\at the next peak. Let it be the period of mass scanning.

Here, the integer selected and set appropriately above is the number of mass scans for one peak, and may be 4, 5, or 10.
Set an integer such as . In this example, the scanning period for the next peak is determined based on the width of one peak, based on the fact that the width of adjacent peaks in a chromatogram does not change much, and the width of the peak gradually increases. Another example of determining the scanning period is to count the time until the differential signal of the output of the total ion detector 5 exceeds a value and then exceed another value set larger than that value, and calculate this time. The scanning period is determined by estimating the width of the peak.
The value obtained by multiplying the above time by the coefficient is set as the scanning period. Still another method is to create a period calculation formula in which the scanning period is a function of time from the time when the sample is introduced into the chromatograph, and to determine the scanning period by a program.

Effects According to the present invention, when performing mass fragmentography,
Since the mass scan is repeated the same number of times for each peak in the chromatogram, a large amount of data is not unnecessarily stored for a wide peak, and the memory capacity can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a waveform graph of an ion acceleration voltage, and FIG. 3 is a graph of an example of a chromatogram. DESCRIPTION OF SYMBOLS 1... Gas chromatograph, 2... Interface, 3... Ion source, 4... Ion acceleration electrode, 5...
...All ion detector, 6...Magnetic field for mass spectrometry, 7...
- Ion detector, 10... ion accelerating voltage power supply circuit. Agent Hiroshi Patent Attorney Valve Hole Diagram 1 Ya 3

Claims (4)

[Claims] (1) A chromatograph mass spectrometer equipped with a control system that variably sets the period of mass scanning according to the width of a peak in a chromatogram so that the number of scans is approximately the same for any peak. (2) Claim 1, characterized in that the width of one peak is detected to set the mass scanning period of the next peak.
Chromatograph mass spectrometer as described in section. (3) The chromatograph mass spectrometer according to claim 1, wherein a mass scanning period for the peak is set by detecting the rising speed of the peak. (4) The chromatograph mass spectrometer according to claim 1, wherein the mass scanning period is set in advance as a function of time.