SU1239766A1 - Method of producing mass spectra of resonance trapping of ions - Google Patents

Abstract

The invention relates to mass spectrometry, in particular, to mass spectrometry of ions, and can be used for the analysis of organic compounds. The aim of the invention is to accelerate and simplify the acquisition of mass spectra of resonant electron capture (REE). In this method, simultaneously with the magnetic scan, the energies of ionizing electrons are scanned in the range covering the energy range of the PZE for all ions of the substance under study with the scanning period T ,. not greater than the minimum sweep time of the peak of a single mass t. In this case, the mass spectrum | is recorded on the paper, which is simultaneously pulled out along with the sweep of the field of the electromagnet. The maximum speed of the magnetic sweep, t-e. the minimum recording time of the mass spectrum is realized at t T. As a device for implementing the method, a digital-to-analog converter is used. 3 pcs. с со (L с 1C оо со ч о Од

Description

I1239

 The invention relates to mass spectrometry, in particular to the mass spectrometry of negative ions, and can be used to analyze organic compounds.

The purpose of the invention is to accelerate and simplify the acquisition of mass spectra of resonant electron capture (REE). In the proposed method, simultaneously

but with a magnetic scan carried out the analyzed substances. There is a scan of the energies of ionizing electrons in the uE range, which covers the REE energy range for all ions of the test substance with a period of one scan T, not 15 greater than the minimum sweep time of the peak of a single mass.

In this case, the mass spectrum is recorded

on paper drawn simultaneously with the sweep of the electromagnet floor, 20 The maximum magnetic scanning speed, i.e. minimum time for the highest sweep speed is reached at the lowest time of the peak of the peak of one mass period of the electron scanned Tj. which is the product of time at each step t. on gov in one scan

The condition t Tt д dy provides the measurement of the ion current at a non-peak height. Due to the n magnetic sweep and the width of the collector mass of ions being focused on the plane of the ion, the peaks of different ions vary in time. Under conv. Tj for some masses t T. However, this is not

mass spectrum recording is realized when

t T

 -l -SK

To implement the proposed method, the mass spectrometer should additionally contain an electron energy sweep device. In the lab as such a device. A computer controlled DAC is used.

The method is carried out as follows.

The computer introduces a program for controlling the operation of the DAC. Using the external communication device (display), in the dialogue mode, the electron energy scanning range is set (the control is based on a digital voltmeter) and the scanning width. Then, the range and speed of the magnetic sweep are set so that the minimum sweep time of the peak of one mass peak is not less than the period of one electron energy scan. The cathode supply voltage is applied and electron energies are scanned. Next, the analyte is introduced into the ionization chamber, and a magnetic scan is turned on while simultaneously drawing ultraviolet recording paper. The FES mass spectrum is recorded on paper as projections of the effective yield curves (EEL).

In the proposed method, in comparison with the known ionization, the electron beam is carried out with an apparently wide distribution of electron energy, which ensures

There is a measurement of the intensity of the ion current for an ion of any mass at the maximum of its CER,

Fig. 1 shows the recording of the mass spectrum on paper, simultaneously pulled out along with the sweep of the electromagnet field, which registers the magnitude of the ion current as a projection of the XEV in Figs.

analyzed substances. five

0

five

0

five

The highest speed of the magnetic sweep is achieved when the shortest sweep time of the peak of one mass peak is equal to the smallest scanning period of the electron energies Tj. which is determined by the product of the delay time at each step t. by the number of K steps in one scan.

The condition t Tt "for a given mass provides a measurement of the ion current intensity at a 100% peak height level. Due to the nonlinearity of the magnetic sweep and the increase in the width of the focused ion beam in the plane of the collector slot with increasing ion mass, the sweep time of the peak of the peaks of ions of different masses is different. Under the condition t Tj for some masses it can be t T. However, this does not change the exact 1 C K,

measurements, since the amplitude value of the ion current is recorded, rather than the integral. Therefore, it is not necessary to coordinate the speed of the magnetic sweep with a period of one electron energy scan to

fulfillment of conditions in willows T „

- min

 T, a, mouth0

(., choose the speed of the magnetic sweep at which - T,

t

 Sc

minimum

45

Example 1. A mini-computer is introduced with an operation control program. Using the display in the dialogue mode, the electron energy scanning range is set to 1–1 V, the number of scanning steps K 5, and the delay time per k; at a t step of 5 ms, i.e.

T

to

Ш 9

To 25 ms. Then install)

wave a range (G - -400 mas.ed.) and a magnetic sweep speed of 10 May / s

 i Ning r -. MIN

at which t - 25 ML (i.e. t 1). The feed voltage of the cathode is applied and scanning of electron energy is started. An analyte is injected into the ionization chamber — 1 µg methyl-2,3,6-tri-0-acet-1-4-0-nitro-o., B-glucopyranoside. Then put in

14 magnetic scan and at the same time stretching the recording paper. The magnetic sweep and the registration paper run out after 40 seconds. The spectrum recorded on paper (figure 2).

Example 2. All operations are carried out as described in Example 1, but the delay time during the scanning step t is 0.5 ms.

 10 t.

40 with a spectrum of pr. T 2.5 ms, and Recorded at the time shown in FIG. 3.

From a comparison of the REE mass spectra obtained for the ratios of the sweep time of the peak of one mass and the period of one energy scan

mime „min

and t 10 T

ix.

electron t

it can be seen that they are almost the same.

Thus, the proposed method ignores the intermediate operation of removing the ERE SR of the analyte and thus allows to significantly simplify the procedure for obtaining the mass spectrum of REE and reduce the time of the experiment, and therefore

and -

ten

and

 15

x.

m

20

25

and requires less analyte.

The positive effect of the method as compared with the known method is that it allows obtaining the REE mass spectrum in a few tens of seconds (40 s) 50-100 times faster.

Claims (1)

Invention Formula A method for obtaining the mass spectra of resonant electron capture on. an electron-beam and magnetic-scanned mass spectrometer, distinguished by the fact that, in order to simplify and accelerate the acquisition of mass spectra, simultaneously with the magnetic scan, the energies of ionizing electrons are scanned in the range covering the energy range of resonant electron capture for ions of the test substance with a single scan period not exceeding the minimum sweep time of the peak of one mass. 1- / G7 1 Editor N. Bobkova Compiled by I.Nekrasov Tehred L. Oleinik Proofreader V. But ha Order 3402/52 Circulation 643 Subscription VNISH1I USSR State Committee Inventions and Openings 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. 2 Fig.Z