JPH0574782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a chromatograph mass spectrometer suitable for performing mass chromatography.

(b) Prior art Mass chromatography is a method in which several types of fragment ions are generated when sample molecules are ionized using an electron impact method, etc., and the way fragment ions are formed characterizes each substance, so mass chromatography is The spectrometer performs repeated scans to select and output several types of ions, and the sample components separated by the chromatograph are introduced into the mass spectrometer to record the increase and decrease of each ion over time. Identification of sample components separated on a graph, etc.
It becomes possible to distinguish components that are insufficiently separated by chromatography.

When performing chromatography, a mass spectrometer repeatedly scans a magnetic field with a magnetic field or a high-frequency voltage with a quadrupole, selectively outputs only specific ions using a computer, and records the detected intensity of each ion. do. At this time, it is necessary to set the period of mass scanning 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 width of the peaks gradually widens later on. 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 for the later, broader peak,
The number of mass scans for one peak becomes extremely large, and if the ion detection output data is stored in the computer's memory and the data is analyzed later, the required memory capacity increases, resulting in wasted storage capacity. was.

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

D. Configuration 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 increases the number of mass scans for one peak, whether it is a sharp peak or a broad peak. To provide a mass chromatography device that is substantially 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 the mass spectrometer, 3 is an ion source, 4 is an ion accelerating electrode, 5 is a total ion detector, 6 is a magnetic field for mass analysis,
7 is an ion detector, and the detected ion intensity data is stored inside the computer 9. Computer 9 also controls the entire device.

A power supply circuit 8 generating an ion acceleration voltage is an excitation power supply circuit 10 for causing a current to flow through the magnetic field. The excitation power supply circuit 8 generates a sawtooth current as shown in FIG. 2 and passes the current through the magnetic field 6.
T in the figure is one period of mass scanning, and this period T is controlled by the computer 9. FIG. 3 is an example of a chromatograph, which is a record of the output of the total ion detector 5. The computer 9 is the total ion detector 5
The output of the chromatograph is sampled at regular intervals, and the chromatographic differential signal is obtained from the difference between adjacent sampling data. Of course, any method can be used to obtain this differential signal. All ions obtained by repeated scanning without using a total ion detector may be added to form a chromatograph, and the signal of this chromatograph may be differentiated.

A mass scanning period for the first peak of the chromatograph is set in the computer 9, and the computer 9 controls the excitation power supply circuit 8 according to this period for the first peak. On the other hand, the computer 9 counts the time from the start to the end of the mass scan, divides the time by an appropriately selected integer, and cuts off the lower digits of the obtained value. Let it be the period of mass scanning.

Here, the integer appropriately selected and set above is the number of mass scans for one peak, and is 4.
and an integer such as 5 or 10. This example uses the width of one peak to determine the scan period of the next peak, based on the fact that the widths of adjacent peaks in a chromatogram do not change much, and the width of the peaks gradually widens. It's up to you to decide.

F. Effect According to the present invention, when performing mass chromatography, mass scanning is repeated approximately the same number of times for each peak in the chromatogram, so it is possible to prevent unnecessary accumulation of large amounts of data for wide peaks. Therefore, effective use of memory capacity is achieved.

[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 accelerating electrode, 5... Total ion detector, 6... Magnetic field for mass spectrometry, 7... Ion detector, 10... ...Ion accelerating voltage power supply circuit, 8...Excitation power supply circuit.

Claims (1)

[Claims] 1 Set the mass scanning period for the next peak based on the width of one peak so that the number of scans is approximately the same for all peaks. A mass chromatography device equipped with a control system.