SU1573408A1 - Apparatus for measuring mass-spectra - Google Patents

Abstract

This invention relates to mass spectroscopy and can be used in quadrupole (monopole) mass spectrometers to measure and indicate mass spectral parameters. The aim of the invention is to improve the noise immunity and reliability of the results of measuring the intensity of the mass spectrum. The device contains a generator, elements AND and OR, analog-digital converter, register, comparison block, counters, frequency divider, threshold element, driver, one-shot, analog-digital comparison block. 2 Il.

Description

The invention relates to mass spectrometry and can be used in quadrupole (monopole) mass spectrometers for measuring and indicating the parameters of mass spectra.

The purpose of the invention is to improve the noise immunity and reliability of the results of measuring the intensity of the mass spectrum.

Fig. 1 is a block diagram of a device for measuring mass spectral parameters; Fig. 2 shows the stress plots at the node points of the device.

The device contains a generator 1, the first element 2 and the second 3 elements And, analog-to-digital Converter (ADC) 4, the element 5 delay, the register. 6, comparison unit 7, display unit 8, second counter 9, frequency divider 10, first counter 11, analog-digital comparison unit 12 (ATS), element OR 33, threshold element 14, driver 15, one-shot 16 and additional element AND 17 ,

The analog signal of the Uc / w spectrum is fed to the first input 18 of the device, and a linearly varying signal, proportional to the mass number UHM, to the second input 19 of the device.

Fig. 2 shows the stress plots at the node points of the device, where a is the signal at the first input 18 of the device, proportional to the mass number; b - the signal at the first output of the frequency divider 10; в - internal synchronizing signal of frequency divider 10; g is the signal at the second output of frequency divider 10; d - the signal of the mass spectrum, arriving at the second input 19 of the device; e, g, and - signals at the outputs, respectively, of the threshold element 14, the driver 15, the one-shot 16; K - reset signal, at the output of the element OR 13 ..

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A device for measuring the parameter mass spectra works as follows.

Depending on the sweep speed, the frequency of the oscillator 1 and the duration of the pulse of the one-oscillator 16 are determined, which is the criterion by which the mass peaks are separated from the pulse interference. It should be slightly more than half the peak duration. Be adjustable threshold threshold element 14, which is the criterion of the intensity of the peaks is determined depending on the noise level, the value of which can be preliminarily measured

At the initial time, nodes 4, 6 | and 8, 12 are given in the initial state by the signal. The initial installation, which is produced by a power-on reset circuit (not shown). At the same time, the A / D converter 4 does not work, because the inhibiting signal from the output of the second element I 3 is present on its control input. When a linearly varying signal is applied to the first input 18, proportional to the UHM mass number, and to the second input 19 of the analog signal of the mass spectrum Ucw, the ADC 12 circuit compares the code recorded in the counter 11 with the analog signal of the UHM mass number,

If the code of the first counter 11 is greater than the code equivalent to the UHM voltage, to the output of the ADC 12 block there is a inhibit signal and pulses from (the generator 1 output does not occur through the first AND 2 element to the input of the counter 11 "If the counter code 11 is less than the code equivalent voltage UHM, then at the second input of the first element And 2 there is an enabling signal, which allows generator 1 to increase the contents of counter 11 and divider 10

per unit. When a signal appears

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at the first output, the frequency divider 10 increases by one the contents of the counter 9, the code of which is fed to the first information input of the display unit 8 to display the current value of the mass number (i-1, i, i + +1, ....).

If there is a peak in the mass spectrum of U cm in section i-1 (Fig. 2e) at time tM, when the peak voltage is 100 5

is equal to the threshold value, the output of the threshold element 14 becomes active, allowing

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pulses from the output of the generator 1 to the control input of the ADC 4. On the leading edge of the output signal of the threshold element 14 in the one-oscillator 16 a positive pulse is formed (Fig. 2i) arriving at the second input of the additional element 17,

The output of the threshold element 14 is in the active state until time t, when the peak intensity becomes less than the set threshold value. At time t, the driver 15 produces a short 5-pulse reset (Fig. 2g) arriving at the first input of the additional element And 17 Since the mass peak of normal duration is present in the spectrum at i-1, the time selection pulse from the output of the single-oscillator 16 and the reset pulse from the output of the driver 15 do not coincide in time. At the outputs of the AND 17 and OR 13 elements, a reset signal is missing and the contents of register 6 are not zeroed. The ADC circuit 4 in the region converts the analog signal of the mass spectrum intensity to a code, the value of which is compared in comparison block 8 with the code stored in register 6.

If the register code 6 is less than or equal to the code from the output of the ADC 4, then the new value of the code is entered into register 6 by the signal from the output of the comparison block 7 and a new measurement is made. If, when comparing, the code in register 6 turns out to be greater than the code from the output of the ADC 4, then the ADC 4 code is not written to register 6.

The process of measurement and analysis is carried out throughout the section, which allows recording the value of the global maximum of the peak intensity (point B, fig 2d) in register 6. At the end of section i-1, which is indicated by the appearance of the signal at the second output of the divider 10 frequency, the leading edge of the signal is rewritten codes of the number of the current mass and the value of the global maximum intensity of the peak in block 8 of the display. On the display panel of the display 8, the number of the mass and the maximum intensity value of the given mass are displayed.

Thus, in contrast to the known device, in which for the maximum intensity value

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the first local maximum can be accepted (point A, fig. 2d), in the proposed device, the value of the global peak intensity maximum (point B, fig. 2d) is measured and output to the display unit.

To prepare the device for measuring the intensity of the next peak of the mass spectrum, the contents of register 6 are reset by a reset pulse (FIG. 2k) from the output of the OR 13 element. This pulse is generated by a delay element 5 that delays the leading edge of the signal from the second output of the frequency divider 10 by time Ј, enough to overwrite the codes of the number of mass and intensity of the peak in block 8 of the display.

Upon receipt at the input 18 of the device signal mass spectrum U .... in to

 see the torus there is a pulse interference on

section i (FIG. 2d), at time tt, the threshold element 14 is triggered, allowing the operation of the ADC 4 for a time t.-t. The shaper 15 and the one-shot 16 produce a reset and selection pulses, respectively, which are fed to the inputs of an additional element And 17, Since the duration of the interference is much less than the width of the peak, the selection and reset pulses coincide in time, and from the output of the element And 17 a reset pulse (fig, 2k) arrives at the first input of the element OR 13. From the output of the element 13, a reset pulse is applied to the additional control input of register 6, producing a reset of the register. Due to this, in the proposed device eliminates the display on the display of the values of the intensity of impulse noise and spurious peaks in contrast to the known device,

The signal from the second output of the frequency divider 10 registers the zero code 6 and the mass number code from the output of the second counter 9 are copied to the display unit 8, and the reset pulse from the output of the OR element 13 prepares the device for measuring the next i + 1 peak.

In the absence of a check and interference in the spectrum of Uc, as well as in the presence of noise, the value of which is less than the specified threshold, the threshold element 14 does not work, prohibiting the operation of the ADC 4, the driver 15 and the one-shot 16. Code

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At the output of the A / D converter 4, the comparison block 7 does not work, and in register-6 the zero code is stored, which, at the end of the current mass number by a signal from the second output of frequency divider 10, is rewritten into display block 8.

Claims (1)

Invention Formula 0 0 A device for measuring the parameters of the mass spectra, comprising a generator, the output of which is connected to the first, inputs of the first and second elements AND, the second input of the first of which is connected to the output of the analog-to-digital comparison unit, the first input of which is the first input of the device, and the second the input is connected to the output of the first counter, the input of which is connected to the output of the first element I and the input of the frequency divider, the first output of which through the second counter 5 is connected to the first input of the display unit, the second input of which is connected to the register output and the first input of the comparison unit, the output of which is connected to the control input of the register, and the second input - to the information input of the register and the output of the analog-digital converter, the analog input of which is the second input of the device, and the control input connected to the output of the second element And, and the OR element, characterized in that, in order to improve the noise immunity and reliability of the results of measuring the intensity of the mass spectrum, a threshold element, a delay element, a driver, a single vibrate op and additional element And, the output of which is connected to the first input of the element OR, the first and second inputs of the additional element And respectively through a driver and a one-shot is connected to the second input of the second element And and the output of the threshold element, the input of which is connected to the analog input of the analog-digital converter, the second output of the frequency divider is connected to the third input of the display unit and the input of the delay element, the output of which is connected to the second input of the OR element, the output of which is connected to an additional pack Aulus yuschim input register. five 0 five 0 five YU P nineteen with-) Editor N. Yatsola Compiled by, Miloslavsky Tehred A. Kravchuk Order 1640 Circulation 514 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and Publishing Combine Patent 1, Uzhgorod, st. Gagarin, 101 ITLJ Lnh Fig Proofreader M, Maksimishinets Subscription