JPS5851621B2 - mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mass spectrometer, and in particular, uses an orthogonal magnetic field single focusing mass spectrometer to perform arithmetic processing on the ion intensity signal in a data processing device after A-D conversion to obtain a mass spectrum, etc. This relates to a water-cooling device.

When trying to process the ion intensity signal from a mass spectrometer using a data processing device after A-D conversion, the ion intensity signal shows a sharp rise in the low mass region, so the peak as a mass spectrum (hereinafter referred to as peak) is Detection is easy, but in a high mass range, the signal is broad, making it difficult to detect the rise of the peak, making peak detection difficult, and there is a need to eliminate this inconvenience.

Conventionally, the sampling period of the A-D converter, which synchronizes the ion intensity signal with the scanning of the mass axis, was uniform from the low mass region to the high mass region, but this invention eliminates the above-mentioned disadvantages. In order to do this, the sampling period of the A-D converter is changed in accordance with the mass axis signal, in other words, the mass number, so that the rise of the peak can be sufficiently detected even in the high mass region 1.

An embodiment of the invention will be described below with reference to the figures.

FIG. 1 is a block diagram of a mass spectrometer according to an embodiment of the present invention, in which a detection signal from a Hall element 2 provided in an electromagnet 1 that generates an orthogonal magnetic field is transmitted as a mass axis signal 4 through an amplifier 3 to A- It is added to the D converter 5, and after A-D conversion, the mass number (
It is input to the data processing device 14 as a mass number) and is calculated.

Figure 2 shows the output voltage of Hall element 2 (strength of magnetic field, vertical axis)
It is a signal characteristic chart showing the relationship between and mass number (horizontal axis).

On the other hand, the output signal of the detector 1 of the analysis tube 6 is passed through the amplifier 8,
The signal is added as an ion intensity signal 9 to the A/D converter 5, and becomes an input to the data processing device after the A/D conversion.

FIG. 3 is a characteristic chart (mass spectrum) showing the relationship between the ion intensity signal (vertical axis) and mass number (horizontal axis) when the orthogonal magnetic field is changed.

In this Figure 3, A is an enlarged view of the ion intensity signal in the low mass region, indicated by the arrow, and has a sharp waveform, and B
is also an enlarged view of the ion intensity signal in the high mass region and has a broad waveform.

In this case, when the A-D converter 5 is operated at the same sampling period, the difference d1 between the ion intensity signal dh1 at the rising edge of the peak in the low mass region and the next sampled ion intensity signal dh2 is Although sufficient detection is possible, the difference d2 between the ion intensity signal dh3 at the rising edge of the peak in the high mass region and the next sampled ion intensity signal dh4 is insufficient for detection.

In this invention, this mass axis signal 4 is converted into a level discrimination circuit 10.
When the level discriminator circuit 10 reaches several preset voltage values as shown in the discriminator circuit characteristic chart of FIG.

The A-D conversion control unit 12 lowers the sampling period step by step (in the direction of increasing the sampling period) using the marker signal 11 (as the mass number increases), and controls the A-D converter 5 using the A-D start signal 13. dh3 of the rising edge of the peak in Figure 3B.
The difference d2 between and dh4 is increased to facilitate detection.

In FIG. 1, 14 is a data processing device, 15 is a control signal, and 16 is a digital output value of the A-D converter 5, which performs processing such as printing out a mass spectrum. This is an example of a mass spectrometer, where 17 is an ion source of the analysis tube 6, 18 is a separator,
19 is a gas chromatograph for sample collection, and 20 is a sample.

In the above embodiment, the level discriminator 10
Although the D conversion control section is controlled, the same effect as in the embodiment can be obtained even if the interval of the A-D start signal 13 is changed by the control signal 15 from the data processing device 14.

The effect of this invention is that the sampling period of the A-D converter can be adjusted in response to changes in the orthogonal magnetic field or ion intensity, as described above, and the mass It is possible to realize an analyzer.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a mass spectrometer according to an embodiment of the invention, Fig. 2 is a characteristic chart of the output voltage of the Hall element and mass number, and Fig. 3 is a characteristic chart of ion intensity signal and mass number. Figure 4 is a characteristic chart of the discrimination circuit. 1...Electromagnet, 2...Hall element, 4
... Mass axis signal, 5 ... A-D converter, 6 ... Analysis tube, 7 ... Detector, 9.
... Ion intensity signal, 10 ... Level discrimination circuit, 11 ... Marker signal, 12 ...
...A-D conversion control unit, 13...A-D start signal, 14...data processing device.

Claims (1)

[Claims] 1 In a device that ionizes a sample and detects an ion intensity signal corresponding to the mass number while magnetically scanning the sample, an A-D converter that converts the ion intensity signal into a digital signal and arithmetic processing of the output of this converter are used. a data processing device that
and a means for controlling the period of operation of the A-D converter by a mass axis signal accompanying magnetic scanning, and the period of operation of the A-D converter is lengthened as the mass number increases, and the period of operation of the A-D converter is lengthened to prevent a broad rise. A mass spectrometer characterized by easy detection of peaks in a high mass range.