SU1346999A1 - Method of checking degree of liquid inhomogeneity - Google Patents

Abstract

The invention relates to analytical, to methods of controlling the composition of liquids, in a wide range of concentrations. The aim of the invention is to improve the measurement accuracy by eliminating the external polar. while expanding the dynamic range of the measured concentrations. The method is implemented by measuring the variables of the potential and the cross-section current generated in the controlled and reference fluids perturbed at the audio frequency. The degree of heterogeneity is judged by the relative change in the impedances of electrode reactions occurring in controlled and reference liquids. The formation of a variable flow potential directly at the electrodes allows one to reduce the level of low-frequency drift, which increases the measurement stability. The impedance of the electrode reaction is determined from the measured values of the alternating flow potential and the flow current in the disturbed fluid. 1 il. § (Л с) 4 3 СО с со

Description

11346999

This invention relates to analytical chemistry and can be used to analyze the chemical composition of liquids and to control the contamination of liquids.

The aim of the invention is to improve the measurement accuracy by eliminating the external polarization of the liquid at

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simultaneous expansion of the dynamic input IITHj minus sign of the allowable range of measured concentrations.

The drawing shows a functional diagram of the device that implements the proposed method.

The vessel 1 is placed inside the pie- 15 zOelectric setting device 2 and the electrokinetic converter 3 is filled with liquid. Electrodes 4 and 5 of converter 3 are connected via switch 6 to an electric signal reading unit 7 containing integrated operational amplifiers 8 and 9. The inverting input of operational amplifier 8 is closed with its output, and the non-inverting input of operational amplifier 6 is connected to the first output of switch 6. Non-inverting the input of the operational amplifier 9 is grounded, and its inverting input is connected to the second output of the switch 6, which is connected to the output of the operational amplifier 9 via a resistor R. The switch 6 has a gap There is a common point, so the electrodes 4 and 5 of the converter 3 are connected either between the non-inverting input of the operational amplifier 8 and the ground, or between the differential inputs of the operational amplifier 9.

inversion of potential E. It is easy to see that

Z: I E, / U | R.

An increase in the concentration of impurities in the controlled fluid is accompanied by a decrease in the parameter Z due to an increase in conductivity.

Determining the impedances of the electrode reaction in the reference (Z) and controlled (Z) fluids, by the relative change of Z relative to Z, calculate the degree of heterogeneity 25 (purity) S of the controlled fluid relative to the reference.

When measuring, the ionic composition of the controlled liquid does not change, since external polarization is absent, and only ion-electron exchange occurs on the measuring electrodes, which increases the measurement accuracy.

The method allows to determine the degree of heterogeneity of dielectric

thirty

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and conductive liquids, as well as their electrical conductivity. The formation of a variable potential of flow directly on the electrodes allows reducing the level of infra-low-frequency drift due to the asymmetry potential, due to which the stability of the measurements increases. Measurement of current flow and flow potential variables makes it possible to use the impedance of the electrode reaction as a carrier of information on the degree of heterogeneity of the controlled fluid, which broadens the dynamic range of the measured concentrations. Tests of the proposed method show its feasibility, simplicity and reliability.

Operational amplifier 8 is a voltage follower, in which, due to the 100% negative feedback, a unit voltage transfer ratio and high input impedance, determined by leakage resistance and integrated circuit and the frequency of the input signal, are realized. Operational amplifier 9 is a current-to-voltage converter (PTN), the current transfer coefficient of which is K, and the input impedance is determined by the ratio of the voltage ratio

R / Kg, where

To

gain amplifier at R oo,

When the fluid oscillates in the capillaries of the porous partition of the transducer 3, for example, sinusoidal

the law set by setter 2 at the output of the operational amplifier 8 generates a variable flow potential Ef, and the output of the operational amplifier 9 is the voltage U - En (R / Z), where Z is the impedance of the electrode reaction flowing on the potential electrode 4 connected to inverti

 the input IITHj minus sign is taken into account

inversion of potential E. It is easy to see that

Z: I E, / U | R.

An increase in the concentration of impurities in the controlled fluid is accompanied by a decrease in the parameter Z due to an increase in conductivity.

Determining the impedances of the electrode reaction in the reference (Z) and controlled (Z) fluids, by the relative change in Z relative to Z, calculate the degree of heterogeneity (purity) S of the controlled fluid relative to the reference.

When measuring, the ionic composition of the controlled liquid does not change, since external polarization is absent, and only ion-electron exchange occurs on the measuring electrodes, which increases the measurement accuracy.

The method allows to determine the degree of heterogeneity of dielectric

and conductive liquids, as well as their electrical conductivity. The formation of a variable potential of flow directly on the electrodes allows reducing the level of infra-low-frequency drift due to the asymmetry potential, due to which the stability of the measurements increases. Measuring the variables of the flow current and the flow potential makes it possible to use the impedance of the electrode reaction as a carrier of information on the degree of heterogeneity of the controlled fluid, which expands the dynamic range of the measured concentrations. Tests of the proposed method show its feasibility, simplicity and reliability.

Claims (1)

Invention Formula The method of controlling the degree of heterogeneity of the fluid, including the measurement of the flow potential of the perturbed standard and controlled liquids, characterized in that, in order to improve accuracy by eliminating the external polarization of the liquid while simultaneously expanding the dynamic range of the measured concentrations, the reference liquid is oscillating, measuring the flow potential and the flow current, these parameters determine impedance of the electrode reaction in the reference fluid, then Compiled by E. Anisimov Editor I. Nikolaichuk Tehred M. Khodanich Proofreader I. Muska Order 5115/42 Circulation 775 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 the same operations are carried out in a controlled fluid, and the degree of heterogeneity is determined by the formula Where 5 (Z, - z) / z, 100%, about - the degree of heterogeneity liquids; i, 2c are the impedances of the electrode reaction in the reference and controlled liquids, respectively.