SU1242788A1 - Method and apparatus for determining concentration of paramagnetic particles - Google Patents

Abstract

This invention relates to an electron paramagnetic resonance technique. The purpose of the invention is to reduce the measurement time of the concentration of paramagnetic particles while increasing the measurement accuracy. The proposed method is based on recording the resonance signals, the conditions where dNr and dN of the absorption of the test and calibration samples, respectively, in the sweep sections with increasing and decreasing magnetic field induction at its different initial values, while the amplitude of the sweep sections of the magnetic field is chosen and the w amplitude of the sections Evolution of an increasing and decreasing magnetic field induction, respectively; W and W, is the width of the resonance absorption lines of the test and calibration samples. The device for carrying out the method comprises an electromagnet, a working resonator located between the pole pieces of the electromagnet and connected by a waveguide path to a SBCh unit and a series-connected microwave detector, a receiving device and an integral intensity calculator, as well as a modulation unit of a magnetic field connected by a first output to a receiving device, and the second with modulation rollers, and a block for setting and scanning the magnetic field. In addition, a calculator of the concentration of paramagnetic particles is introduced into the device, the output of which is connected to the output of the integral intensity calculator. The unit for setting and scanning the magnetic field is performed consisting of a scanning device, a setting device for the sweep amplitude and a setting device for the initial value of the magnetic field induction, 2 s.p. f-ly, 1 silt, (L S

Description

one

The invention relates to an electron paramagnetic resonance (EPR) technique and can be used in the design of EPR radio spectrometers and other automatic monitoring of substances to determine the concentration of paramagnetic particles.

The purpose of the invention is to reduce the measurement time of the concentration of paramagnetic particles with increasing measurement accuracy.

The drawing shows a block diagram of a device implementing a method for determining the concentration of paramagnetic particles,

An example. According to the proposed method for measuring the concentration of paramagnetic particles, including sequential registration during scanning of the magnetic field of non-overlapping EPR signals placed in the same volume of the working resonator of the test and calibration samples, and comparing their integrated intensity in accordance with the ratio

1242788

The time to determine the concentration is determined by the time taken to record the resonance absorption spectra of the test and sample samples, which depends on the amplitude of the sweep in areas with increasing and falling magnetic field induction.

When registering at different scanning areas of non-interleaved) 0 EPR lines of the same form, the ratio of the calculated values of their integrated intensities is determined by the expression

15

AN-Price

(3)

Where

A - nominal (true)

; 0

25

the values of the integral intensities: l1-gnii of the EPR of the test and calibration samples, respectively, at any values of the amplitudes of the sweep in the areas with increasing and decreasing magnetic field induction, if condition (2) is satisfied.

N

1VT AI;

BUT

BY

where Nj and N are the concentration of paramagnetic particles in the test and calibration samples;

Hell and AJ, - integral intensity of the resonance absorption lines of the test and calibration samples,

the recorded EPR signals of the test n calibration samples are carried out respectively at the sweep sections with increasing and decreasing induction of the magnetic field at its different initial values, and the amplitude of the sweep sections of the magnetic field is chosen from the condition

four.

W

and

W.

(2)

de ANR, „and dNr5,

the amplitude of the sweep sections with increasing and falling magnetic field induction, respectively; W.j and W ,, is the width of the resonance absorption lines of the test and calibration samples;

m

15

AN-Price

(3)

Where

A - nominal (true)

the values of the integral intensities: l1-gnii of the EPR of the test and calibration samples, respectively, at any values of the amplitudes of the sweep in the areas with increasing and decreasing magnetic field induction, if condition (2) is satisfied.

Thus, the fulfillment of condition (2) makes it possible to determine the integrated intensities of the recorded EPR signals of the test and calibration samples by numerically integrating them with a change in the magnetic field to much smaller limits than is necessary to find their nominal (true) values. At the same time, the registration of these signals, respectively, at parts with increasing and decreasing magnetic field strength, reduces the recording time and, consequently, shortens the measurement time of the concentration of paramagnetic particles in the test substance, and the exception (due to the decrease in integration) of the resonant absorption curve areas on which the recorded signals are comparable with the amplitude of the noise; they provide an increase in the accuracy of the determination: concentration in the test substance. In case of 10, time

 mc of measurement is reduced by more than

order, and the measurement error of concentration does not exceed 1-2%,

3

- A device for determining the concentration of paramagnetic particles consists of a working resonator I, located between the pole tips of the electromagnet 2 and connected by a waveguide path to the microwave unit 3 and the microwave detector 4 connected in series, the receiving device 5 and the integrated intensity calculator 6, the magnetic field modulation unit 7 connected by a first output to a receiving device 5, and the second to a modulating coil 8, unit 9, setting and sweep of a magnetic field consisting of a scanning device 10, a sweep amplitude sensor 11 connected by an output to a first input of the sweep device 10 and a magnetic field induction initial setting unit 12 connected to the second input of the scanning device 10, the output of which is connected to the control inputs of the initial amplitude sweep generator 10, the initial magnetic induction value 12 the floor and to the coils of the electromagnet 2, and the transmitter 13 of the concentration of paramagnetic particles, the input of which is connected to the output of the calculator 6 of the integral intensity,

The working cavity 1 is placed in the test and calibration samples, with the paramagnetic substance being selected as the latter with a g factor that is different from the g factor of the test sample. After setting up the device consisting in setting the initial values of the magnetic field in the setter 12 in the sweep sections with increasing and falling magnetic field induction and setting 11 amplitude values in the setpoint generator (dNr c and dNr (,) sweep on these sections satisfying the conditions of independent registration EPR spectra of the investigated and calibration samples and the condition (2), includes the task block 9., and the sweep of the magnetic field.

Unit 9 with the help of an electromagnet 2 forms a sweep area with increasing magnetic field induction. As a result, when resonant conditions are passed, the first derivative of the resonant absorption signal of the sample under study at the modulation frequency is formed at the output of the detector 4, amplified, recorded

25

242788. four

at the frequency of modulation and is digitized in the receiving device 5 and fed to the input of the calculator 6 of the integrated intensity. 5 After the end of the sweep section with increasing induction of the magnetic field, the calculated intensity of the integrated intensity O of the EPR line of the test substance is calculated in the calculator 6 by double calculated integration, and the output signal of the device 10 of the sweep of the 9 task and scan of the magnetic field is stored in the calculator 13 switches the setpoint generator II amplitude and the setpoint adjuster 12 of the initial value of the magnetic field induction to the state ensuring the formation of the sweep area - from the 20 falling down nduktsiey magnitnog; about

floor in accordance with the parameters previously set in block 9.

In the process of forming a sweep section with a falling magnetic field induction, the first derivative of the resonant absorption signal of the calibration sample is recorded, and after its completion in the concentration concentration calculator 13, the value 0 of the integral intensity calculated in the integral intensity calculator 6 is found and in accordance with the expression (1) The concentration of paramagnetic particles in the test sample is calculated.

Claims (2)

Invention Formula 0- 1. Method for determining the concentration of paramagnetic particles, which includes alternately registering in the process of scanning the magnetic field of non-overlapping resonant absorption signals placed in the same volume of the working resonator of the test and calibration samples and comparing their integral intensities in accordance with by relation . where N and iW | - concentration paramagnetic particles in the test and calibration samples; A and A are the integral intensities of the resonance absorption lines of the test and calibration samples, characterized in that, in order to reduce the measurement time of the concentration of paramagnetic particles while increasing the measurement accuracy, the resonance absorption signals of the test and calibration samples are measured respectively at sites sweep with increasing and falling magnetic field induction at its different initial values, and the amplitude yiacTKOB sweep magnetic field choose from the condition -52 1- -g- -2 -, where dN and Wf, W,; IdHpj is the amplitude of the sweep sections with increasing and falling magnetic field induction; W, and W are the polarine absorption lines of the test and calibration samples. 2. A device for determining the concentration of paramagnetic particles, containing an electromagnet, a working resonator, located between the pole tips of an electromagnet and connected by a waveguide path to a microwave unit and connected in series a microwave detector, a receiver and an integral intensity calculator, a modulation unit of a magnetic field connected by a first output to a receiver, and a second to modulation katutpka, a task and sweep unit of a magnetic field connected to an electromagnet, the magnetic field setting and scanning unit is made up of a scanning device, a sweep amplitude setting device connected to the first input of the scanning device, and a setting device for the initial magnetic field induction value, connected by the output to the second input of the sweep device, the output of which is connected to the control inputs of the generator of the sweep amplitude and setting device: and the initial value of the magnetic field induction, and the device is used to calculate the concentration of paramagnetic particles, the input of which is connected to the output of the integral intensity calculator. Compiled by A. Fedorov Editor N. Rogulich Tehred N. Bonkalo Corrector | B, Sinitska Order 3695/40 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, 4/5 Raushsk nab. Production and printing company, Uzhgorod, st. Project, 4