RU1540U1 - VOLTAMPEROMETRIC SENSOR FOR DETERMINING MASS CONCENTRATION OF METAL IONS IN AQUEOUS MEDIA - Google Patents

Abstract

VOLTAMPEROMETRIC SENSOR FOR DETERMINING MASS CONCENTRATION OF METAL IONS IN AQUEOUS MEDIA, containing an electrochemical cell including a reference electrode, auxiliary and rotating working electrodes, characterized in that the auxiliary electrode is made in the form of a glassy carbon electrolyzer, and the working electrode is a casing made of a ferrule made of a clip a glass-carbon rod and a conductive sleeve in contact with the glass-carbon rod are pressed in, the contact point of which s fused by Wood's alloy.

Description

The utility model relates to the field of industrial chemistry, namely, to: tools 1.1 for measuring the mass concentration of metal ions in aqueous media by voltammetric method and can be used in the analysis of drinking, natural and waste water, as well as food raw materials from foodstuffs after their mineralization and transfer to a water solution.

Known voltammetric sensor. For determining the mass concentration of metal ions in aqueous media / and.with. USSR . 1122961, O-01 // 27/48, 06.24.83. /. The sensor contains an electrochemical cell, including a reference electrode, an auxiliary and two working electrodes, one of which is rotating. Working electrodes are made of graphite.

Sensor given; The structure has insufficient sensitivity associated with the use of graphite as a material for working electrodes. Graphite is a soft carbon material with pores and cracks into which the components of the test solution are trapped during the measurement process. The components of the solution, leaving B pores, are restored and during the measurement process, the surface of the working electrode does not completely regenerate to the original state, which leads to a decrease in sensitivity and reproducible measurements.

In addition, the use of an auxiliary electrode, the area of which is commensurate with the area of the working electrodes, is due to the additional accumulation of metal atoms from the studied region

The objective of the utility model is to create a highly sensitive sensor that allows measurements of the mass concentration of metal ions in aqueous media in the range of trace amounts with a high degree of reproducibility of measurement results.

The problem is solved by the fact that in the voltammetric sensor, to determine the mass concentration of metal ions in aqueous media containing an electrochemical cell, including an electrodes 5) comparison, auxiliary; The working electrode is rotated, the auxiliary electrode is made in the form of a glassy carbon electrolyzer, and the working electrode is a cage made of an electrically insulating material into which a glassy carbonaceous rod is pressed in. An electrical wire sleeve is in contact, which contacts the glassy carbon rod, the contact point of which is fused with a tsA alloy.

The implementation of the auxiliary electrode in the form of a glassy carbon electrolyzer allows you to combine two functions in it at the same time: capacity. For the room, the test solution and the auxiliary electrode of a large area. This ensures a low current density of the recovery of metal ions, as a result of which there is no appreciable accumulation of metal atoms from the test solution on the surface of the auxiliary electrode during the measurement, which significantly increases the sensitivity of the sensor by half to determine the mass concentration of metal ions at 0.1 μg / l ..

The large surface area of the auxiliary electrode in comparison with the area of the working electrode also allows one to reduce the negative effects associated with the oxidation of the auxiliary electrode and the accumulation of metal atoms on it using the inverse voltammetric analysis method, which increases the reproducibility of the measurement.

The use of glassy carbon as the material of the working electrode makes it possible to increase the readability. And reproducibility of the measurement due to the absence of pores on the surface of the electrode, which prevents the penetration of components deep into the electrode and ensures good regeneration of the electrode surface.

Melting by the alloy and the contact point of the glassy carbon rod with the electrically conductive sleeve eliminates the oxidation of the glassy carbon rod at the point of mechanical contact, which occurs during long-term operation of the sensor. Elimination of oxidation at the point of contact allows maintaining a low total resistance of the working electrode, which increases the measurement sensitivity.

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The utility model is illustrated by drawings. In FIG. 1 - common probe sensor; chfig. 2 - the same as above; - - /; (Ig. 3 - assembly drawing of the working and auxiliary

an electrode; $ oag. 4 is a voltasherogram of a solution containing Pl.UZn ions.

A voltagesherometric sensor containing an electrochemical cell, including a reference electrode 1, a rotating working electrode 2, an auxiliary electrode made in the form of a glassy carbon electrolyzer 3. The working electrode 2 is a clip 4 of an electrically insulating material, for example, fluoroplastic 4, into which a glassy carbon rod 5 is pressed into and electrically conductive sleeve 6, konz activated with a glassy carbon rod 5, the contact point of which is fused with a Wucz alloy / M.Kh. Karapetyants, S.I. Drakin General and Inorganic Chemistry Ed. Chemistry, M.1981, p. 432 /

The electrically conductive sleeve 6, for example made of Latvian, has an internal thread 8, with the help of which the working electrode 2 1 is clamped on the bp axis:: angle 9. The axis of rotation 9 is installed in the holder 10 and connected by a flexible electrically insulating coupling 11 with the shaft 12 of the electric motor 13. The engine 13 is fixed on the pin 14 to the pank-holder 15. The Pyanka-g holder 15 is mounted on the housing 16, inside which is located the power supply and the lettering 17 of the engine 13. The outputs 18, 19, 20, respectively, of the working 2, auxiliary 3 and reference electrode 4 are connected to the polar ografu / not shown /. The power supply and control unit 17 of the engine 13 is also connected to the polarograph.

The sensor operates as follows.

A sample of the test aqueous solution is placed in a glassy carbon electrolyzer 3 and a background solution is added to it. Then the electrolyzer is installed in the holder 10.

Between the working electrode 2 and the reference electrode 1, the working voltage of accumulation of metal atoms on the surface of the working electrode 2 is set. At the same time, the operating voltage is supplied from the power supply unit and the control unit 17 of the motor 13 to ensure rotation of the working electrode 2.

After the set accumulation time has elapsed, the rotation of the working electrode 2 is stopped and after a pause of 10-15 seconds / quiet time /, a scan of the polarizing voltage from the polarograph is applied to the integral final value.

At the same time, the current value is recorded in the circuit of the working electrode 2, which includes the oxidation current of the accumulated metal atoms. The magnitude of the changing current of the working electrode and the polarizing voltage are recorded on a two-coordinate polarograph recorder in the form of a graph of potential, called a voltammogram. The peaks recorded on volt1 perogrash (e peaks are the oxidation currents of metal atoms, and the position of the peak on the potential scale identifies the nature of the metal, and the peak intensity on the current scale is proportional to the concentration of metal ions in the solution.

We give an example of a specific measurement.

. Figure 4 shows the voltammogram of a solution containing copper ions / 50 μg / l /, lead / 50 lzhg / l /, cadmium / 50 μg / l / and zinc / 50 μg / l /.

The tables below show the measurement results produced by the sensor of the claimed design.

Table 1 provides data illustrating the sensitivity of the sensor of the claimed design.

The sensitivity was determined by the method introduced, found on the example of solutions of state standard samples / 1. GSO of the composition of aqueous solutions of lead ions, kit,

registry. 7002-93;

2. GSO of the composition of aqueous solutions of cadmium ions, kit. No. 1K, registry. I 7001-93;

3. GSO of the composition of aqueous solutions of copper ions, ZK set,. registry. 11,703-93;

4. GSO of the composition of aqueous solutions of zinc ions, kit .M4K, registry. J 7004-93./

As follows from table 1, the device provides a determination of ions at a concentration level of 0.1 μg / l with a standard deviation of 0.

Table 112 provides data illustrating the reproducibility of metal ion determinations at various concentrations. .

Reproducibility was established using solutions of state standard samples

/ 1. GSO composition of aqueous solutions of lead ions, kit ,,. registry. .7002-93;

2. GSO composition of aqueous solutions of cadmium ions, JWK kit,. registry. I 7001-93 ;,

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4. GSO composition of aqueous solutions of zinc ions, set 4K,

registry. .№ 7004-93./.

As follows from table 2, the device provides reproducibility of the determination of Dflb-Q, for daapozona concentrations of S-10Omkg / y), which is significantly lower than the standard deviation compared with the prototype.

Thus, the voltammetric sensor of the claimed design allows the simultaneous analysis of ions of copper, lead, cadmium and zinc in aqueous solutions with high sensitivity and reproducibility of the measurement results.

In addition, the sensor can be used in the analysis of arsenic, mercury, manganese, tin, bismuth, thaw, indium, sfm and elements in aqueous solutions.

Director of BTF Vol LLP: ySh

Authors: Kondratiev Bi Kiryakov B.C.

/ J /

Kiryakov B.C.

Determination of readout measurements of the mass concentration of copper, lead, cadmium and zinc ions using the inventive sensor.

Table 1.

Conclusion: The root-mean-square deviation according to the results of the determinations is 0.08; the device provides a determination of the mass concentration of ions of honey, cadmium lead and zinc at a level of 0.1 μg / l with a standard deviation of 0.08, which exceeds the prototype in metrological characteristics.

Determination of standard deviation / standard deviation / results of determination of the mass concentration of ions of copper, lead, cadmium and zinc using the inventive sensor. The concentration of the detected ion, mcg / l Conclusion:

Table 2. The number of determination results 1 2 345 the device provides the determination of metal ions at a concentration of 10-100 μg / l with a standard deviation of 0.03-0.04, which significantly exceed the metrological parameters of the prototype. (JO

Claims (1)

VOLTAMPEROMETRIC SENSOR FOR DETERMINING MASS CONCENTRATION OF METAL IONS IN AQUEOUS MEDIA, containing an electrochemical cell including a reference electrode, auxiliary and rotating working electrodes, characterized in that the auxiliary electrode is made in the form of a glassy carbon electrolyzer, and the working electrode is a casing made of a ferrule made of a clip a glass-carbon rod and a conductive sleeve in contact with the glass-carbon rod are pressed in, the contact point of which s fused by Wood's alloy.