Polarographic oxygen sensor

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement of values of hydro-chemical-physical parameters of water medium and can be used separately or in multi-channel converter of hydro-chemical-physical parameters of water medium, for measurement of content of dissolved oxygen in water medium, in particular in fresh and sea water during ecological research. According to invention polarographic oxygen sensor comprises body filled with electrolyte with hole in upper part, membrane made of at least two layers of gas-permeable material, tightly closing said hole, two electrodes – cathode adjacent to membrane, and anode placed in volume of electrolyte, lower support layer of membrane made of material allowing unobstructed passage of oxygen molecules dissolved in water to cathode with strength characteristics, providing strength at dynamic and static loads, occurring during operation, and upper selective layer is made in form of polymer coating deposited on support layer.

EFFECT: technical result is reduction of time constant with provision of required service life of sensor.

1 cl, 1 dwg

 



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention is aimed at determining gold (III) in aqueous solutions by differential pulse voltammetry. A method of determining gold via a differential pulse voltammetric method in aqueous solutions includes electrochemical concentration of gold (III) ions on the surface of different types of graphite electrodes in the form of gold followed by dissolving and recording cathode current-voltage curves; accumulating gold (III) ions on the surface of the graphite electrode in a mixed solution for 60 s with electrolysis potential of -0.8 V; measurements are taken on a background of 0.1 M NaOH, followed by recording cathodic peaks and plotting current-voltage curves in differential pulse mode with a sweep rate of 80 mV/s; concentration of gold (III) ions is determined from the height of the cathodic peak in the potential range of -0.2 V to -0.5 V relative to a saturated silver chloride electrode by standard addition method.

EFFECT: invention enables to reduce the maximum and lower boundary of determined gold concentrations on a cathodic peak obtained after electrooxidation of gold on a graphite electrode by differential pulse voltammetry.

1 dwg, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: methionine is transformed from combined feed into a solution. Methionine is measured by using an analytic signal of methionine recovery at a potential of 0.315 V in a borate buffer solution at pH 9.18 in a mercury-film electrode (MFE). A methionine recovery limiting current gain is linearly related to a concentration increase in a reference solution as 2.6·10-4 mole/l to 2.0·10-3 mole/l. A potential sweep rate has made 0.06 V/s. A methionine detection limit of 2.0·10-4 mole/l is high enough to be applicable to evaluate its quantity in the combined feed.

EFFECT: higher sensitivity and rapidity of the method for measuring methionine in the combined feed by cathode voltammetry.

1 ex, 1 tbl, 3 dwg

FIELD: measuring equipment.

SUBSTANCE: invention relates to equipment for measurement of dissolved gas content in liquid and gas media, is intended, essentially, for usage in oceanographic apparatus and may be used in mining, chemical industry, in various technological and ecological systems for measurement and control of dissolved gas content in the medium under study. Essence: according to the first implementation version (Fig. 1) the barometrically compensated electrochemical measuring gas analyser contains a body (1), a sealed chamber (12) that has a capillary (13) and is filled with electrolyte, a cathode (16) and an anode (17) or an anode system which contact the electrolyte and are connected to a registering unit (18) represented by a transducer converting cathode current into an output signal. The cathode (16) is positioned at the capillary (13) output into the ambient environment. The cathode (16) and the capillary (13) are separated from the ambient environment by a round-shaped selectively permeable membrane (6). The membrane (6) is drawn to the gas analyser cathodic surface and is fixed thereon along a closed line by a lid (7) connected to the coupling nut (10). The gas analyser contains a barometric compensator (11) in the form of an elastic element separating the electrolyte in the chamber (12) from the ambient environment. The capillary (13) is designed in a pass element (3). One end of the pass element (3) with a sealing element (2) is installed in the body (1), rigidly or so that to enable movement. The other end of the pass element (3) with a sealing element (4) is passed through a sleeve (5) hole. The sleeve (5) is thread-mounted in the lid (7) which is installed with a sealing element (9) in the coupling nut (10). The coupling nut (10) is thread-mounted on the pass element (3). The membrane (6) edge part is clamped between the lid (7) shoulder and the sleeve (5) butt-end surface. The anode (17) or anode system is positioned in the capillary (13) or in the chamber (12). The chamber (12) is the space formed by the pass element (3) and the body (1). Such space is separated from the ambient environment by the barometric compensator (11) in the form of an elastic wall, for example, a rubber jacket fixed on the body (1) and in the pass element (3). The space formed by the pass element (3), the sleeve (5), the lid (7) and the coupling nut (10) is filled with an electroinsulating liquid (15), for example, oil. Such space, via the thread between the coupling nut (10) and the pass element (3), communicates with the space formed by the barometric compensator (11), the body (1) and the coupling nut (10), is filled with electroinsulating liquid (15) and separated from the ambient environment with an additional barometric compensator (14) in the from of an elastic wall, for example, a rubber jacket fixed on the body (1) and on the coupling nut (10). The second invention version (fig. 2) differs from the first one by the fact that the pass element (3) is installed in the body (1) with a sealing element (2) and so that to enable movement and is passed through the sleeve (5) hole with a sealing element (4). The sleeve (5) has radial holes. The sleeve (5) is installed on the body (1) with one end with a sealing element (6) so that to enable movement; with the other end, it is thread-mounted in the lid (8). The lid (8) is installed with a sealing element (10) in the coupling nut (11) that is thread-mounted on the body (1). The membrane (7) edge part is clamped between the lid (8) shoulder and the sleeve (5) butt-end surface. The anode (18) or the anode system is positioned in the capillary (14) or in the chamber (13). The chamber (13) is the space formed by the pass element (3), the sleeve (5) with its radial holes and the body (1). Such space is separated from the ambient environment by the barometric compensator (12) in the form of an elastic wall sealing the sleeve (5) radial holes for example, a rubber jacket fixed on the sleeve (5). The coupling nut (11) has radial holes positioned near the sleeve (5) radial holes. The space formed by the barometric compensator (12), the sleeve (5), the lid (8), the coupling nut (11) with its radial holes and the body (1) is filled with electroinsulating liquid (16), for example, oil. Such space is separated from the ambient environment by an additional barometric compensator (15) in the from of an elastic wall sealing the coupling nut (11) radial holes and the thread connection between the body (1) and the coupling nut (11), for example, in the from of a rubber jacket filled on the body (1) and the coupling nut (11).

EFFECT: ensuring the main metrological characteristics of the device (sensitivity and long-term stability) as well as membrane material saving.

FIELD: medicine.

SUBSTANCE: invention describes a method for lipoic acid measurement in biologically active additives by cathode voltammetry involving transferring a substance from a sample into a solution and taking voltammetric measurement; the cathode voltammetry is performed on a mercury-film electrode at potential -0.373 V of a relatively saturated silver-chloride electrode with borate buffer solution pH 9.18 at continuously current potential trace at 0.06 V/s with the determined lipoic acid content range from 4.5·106 to 1.1·10-3 mole/l.

EFFECT: improving sensitivity and expressivity of the method for measuring lipoic acid in tabletted BAAs by cathode voltammetry.

1 tbl, 1 ex, 3 dwg

FIELD: instrumentation.

SUBSTANCE: gas analyser (fig. 1) comprises electrolytic chamber 1 with capillary 2 extending to gas analyser cathode surface. Said chamber and capillary are filled with electrolyte. Device comprises anode 3 in direct contact with chamber electrolyte and cathode 4 arranged at gas analyser surface nearby capillary outlet area. Cathode and capillary are isolated from ambient medium by selective-permeability ring-shape membrane 5 attracted to cathode and capillary and locked at gas analyser cathode surface. Said membrane is attracted and locked by cover 6 composed of turned over cup with axial bore in its bottom and coupled with coupling nut 7. Said membrane is attracted by its edges squeezed between cover bottom and seal ring 8 arranged inside said cover and features preset modulus of elasticity and depth. Membrane locking is ensured by said cover over closed line with the help of rib shaped to blunt angle. Conductors 9, 10 are designed to derive output signal from anode 3 and cathode 4. Said conductors are connected to gas analyser output signal recorder 11. The second version (fig. 2) differs from said first one in that membrane is attracted and locked by different elements. Electrolytic chamber 1 with capillary 2, anode 3 and cathode 4, selective-permeability ring-shape membrane 5 attracted to cathode and capillary and locked at gas analyser cathode surface by the rib in closed line. Note here that at joint between membrane and cover, the latter features low friction factor. Device comprises coupling nut 7. Attracting element 8 is arranged inside turned cover 6 and composed of over cup with axial bore in its bottom. Cover 6 and attracting element 8 are articulated. Coupling nut 7 is connected with attracting element 8. Said seal ring 9 is inside element 8 and features preset modulus of elasticity and depth Membrane 5 is attracted to cathode and capillary by element 8 with the help of nut 7 so that membrane edges are squeezed between attracting element bottom and seal ring 9. Conductors 10, 11 tap output signal from said anode and cathode and are connected to output signal recorder 12. The third version (fig. 3) differs from said first one in that membrane is attracted and locked by different elements. It differs from above versions in the following. Electrolytic chamber 1 with capillary 2, anode 3 and cathode 4, selective-permeability ring-shape membrane 5 attracted to cathode and capillary and locked at gas analyser cathode surface by the rib in closed line. Device includes coupling nut 7 arranged inside cover 6 and rigidly coupled therewith. Attracting element 8 composed by washer is arranged inside coupling nut 7, at its bottom, while seal ring 9 with preset modulus of elasticity and depth is arranged therein. Note here that at joint between element 8 and nut 7 features to friction factor. Said membrane is attracted to element 8 so that its edges are squeezed between element 8 and ring 9. Conductors 10, 11 tap output signal from said anode and cathode and are connected to output signal recorder 12.

EFFECT: simplified and reliable design, efficient sealing, lower membrane material input.

5 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to electroanalytical chemistry and can be used to analyse drinking water surface water and other water bodies. A method for voltammetric determination of phenol in water and water bodies using a three-electrode system, which includes pre-modifying electrochemical treatment of a glass-carbon indicator electrode of the system, measuring phenol concentration in the water, including electrochemical deposition of phenol on the modified surface of the indicator electrode from the analysed water, subsequent electrooxidation of phenol while varying potential of the indicator electrode, detecting an analytical signal on the current versus voltage curve, identifying a phenol peak on the current versus voltage curve and determining phenol concentration from the value of the phenol peak, characterised by that pre-modifying electrochemical treatment of the indicator electrode is carried out in 0.2 M aqueous ammonium sulphate solution with addition of acetone in volume ratio of 19:1, respectively. A method in which electrodes of the measurement system - indicator, comparison and auxiliary electrodes - used are identical glass-carbon rod electrodes, and where pre-modifying electrochemical treatment of the indicator electrode also includes treating the surface of the comparison electrode and the auxiliary electrode in 0.1 M aqueous potassium hydroxide solution with addition of acetone in volume ratio of 19:1, respectively.

EFFECT: improved method.

3 cl

FIELD: chemistry.

SUBSTANCE: method of determining aflatoxin B1 includes the following operations: transferring aflatoxin B1 from a sample into a solution and carrying out voltammetric accumulation of mycotoxin in a stirred solution for 30 s at electrolysis potential of (0.0±0.05)V relative to a saturated silver chloride electrode on an ammonium chlorate (NH4ClO4) background, pH 2.0-3.0, followed by detection of anodic peaks with sweep rate of 30 mV/s, and determining concentration of aflatoxin B1 from peak height in the range of En=(0.625±0.045)V by standard addition method.

EFFECT: invention enables use of electrodes made of nontoxic material and determination of aflatoxin B1 by anodic stripping voltammetry in the presence of dissolved oxygen without further addition of a reducing agent to the background electrolyte, wider range of determined concentrations and a technique for rapid evaluation of aflatoxin B1 in 30-40 minutes.

2 tbl, 2 ex, 1 dwg

FIELD: chemistry.

SUBSTANCE: method of mercury identification by cathode-anode voltammetry with the application of an electrode and background solutions includes the following succession of actions. First, a glassy carbon electrode is kept in a background solution at a potential from -0.4 to - 0.7 V for 120 s, then it is switched to a potential from + 0.4 to + 0.5 V and is kept for 10 s with the following registration of voltamperogram with a linear involute of the potential in the range from 0.4 V at 100 mV/s and a peak of the mercury reduction, observed at the potential in ranges (-0.05-0.05) V, and linear dependent on the mercury concentration in water solutions. A mercury signal is registered and evaluated by a method of additives of certified solutions relative to a saturated silver chloride electrode.

EFFECT: invention makes it possible to determine a small quantity of mercury in a water solution by the method of cathode-anode voltammetry.

2 tbl

FIELD: chemistry.

SUBSTANCE: method of molybdenum identification includes the determination of a complex compound of molybdenum with diethyldithiocarbaminate by cathode voltammetry . According to the invention 0.02 ml 1·10-4 M of sodium diethyldithiocarbaminate are introduced into a universal buffer solution, then a sample, which contains molybdenum is introduced, the solution is mixed for 10-30 s, a potential of electrolysis +0.4 V is supplied for 180 s on a glassy carbon electrode and current of a molybdenum peak is registered at a speed of the potential involute of 100 mV/s. A signal of molybdenum is registered and evaluated by a method of additives of certified solutions relative to a saturated silver chloride electrode.

EFFECT: invention makes it possible to reduce a lower boundary of determined contents of molybdenum by 2-3 orders.

2 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: lactic acid is transferred from a sample into a solution and voltammetric accumulation of lactic acid in the stirred solution is performed while bubbling with an inert gas for 30 s and with electroaccumulation potential of 1.2-1.4 V relative to a saturated silver chloride electrode on a background electrolyte of 0.1 M Na2HPO4, followed by detection of cathode peaks in differential mode of recording voltamperograms with potential sweep rate of 30-40 mV/s; concentration of lactic acid is determined from peak height in the potential range of 0.25-0.40 V by a standard addition method.

EFFECT: method is simple, does not require a large amount of reactants and labour costs.

2 ex, 1 tbl

FIELD: measuring equipment.

SUBSTANCE: sensor for measuring concentration of fluid-soluble gas includes: housing (100), which is coated with selectively permeable membrane (60) and is filled with fluid medium (30) of sensor; at least two electrodes (10, 20) located inside housing (100), wherein said electrodes (10, 20) are coated with fluid medium (30) of sensor in at least one detection site (40); and ion-balancing means (50) located inside housing (100) and at a distance from detection site (40) of electrodes (10, 20), and which is in contact with fluid medium (30) of sensor, to remove contaminating ions from fluid medium (30) of sensor.

EFFECT: invention enables formation of a device for measuring concentration of fluid-soluble gas with improved resistance to drift and low production costs.

15 cl, 7 dwg

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement of values of hydro-chemical-physical parameters of water medium and can be used separately or in multi-channel converter of hydro-chemical-physical parameters of water medium, for measurement of content of dissolved oxygen in water medium, in particular in fresh and sea water during ecological research. According to invention polarographic oxygen sensor comprises body filled with electrolyte with hole in upper part, membrane made of at least two layers of gas-permeable material, tightly closing said hole, two electrodes – cathode adjacent to membrane, and anode placed in volume of electrolyte, lower support layer of membrane made of material allowing unobstructed passage of oxygen molecules dissolved in water to cathode with strength characteristics, providing strength at dynamic and static loads, occurring during operation, and upper selective layer is made in form of polymer coating deposited on support layer.

EFFECT: technical result is reduction of time constant with provision of required service life of sensor.

1 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: said ionic liquid comprises, at least, one protic ammonium cation with, at least, one hydrogen atom being dissociated, wherein the said, at least, one protic ammonium cation reacts with the given gas by deprotonation. herewith the said, at least, one protic ammonium cation has a pKa value less than 9.25. The invention also relates to the method for detecting a target gas.

EFFECT: gas sensor overcomes the problems associated with the use of aqueous electrolytes.

14 cl, 5 dwg

FIELD: chemistry.

SUBSTANCE: for liquid electrolyte used in electrochemical gas sensor for detecting NH3 or NH3 - containing gas mixtures, the present claim provides that said electrolyte contains at least one solvent, one conductive salt and/or one organic mediator. Wherein the conductive salt represents an ionic liquid, an inorganic salt, an organic salt, or a mixture of these substances. Preferably, the electrolyte consists of (i) water, propylene carbonate, ethylene carbonate or mixtures thereof as the solvent; (Ii) LiCl, KCl, tetrabutylammoniatoluenesulfonate or 1-hexyl-3-methylimidazolium tris (pentafluorethyl) trifluorophosphate as conductive salt; and (iii) tretbutylhydroquinone or anthraquinone-2-sulfonate as an organic mediator.

EFFECT: improved properties.

44 cl, 2 dwg

FIELD: analytical chemistry.

SUBSTANCE: substance is subject to preliminary concentrating during 300 sec at potential of electrolysis of (-1,2) V by using special device. Glass-carbon electrode is used as working electrode. Polarization curves are registered subsequently at ac potential development at speed of 300 mV/sec. Concentration of amiodarone is found from peak value within the potential range of 0,1-0,3 V relatively chlorine-silver electrode in 0,005 mole/l nitrate ammonium solution that is prepared on the base of 0,015 mole/l sodium hydrocarbonate solution.

EFFECT: improved sensitivity of method.

1 dwg, 4 tbl

FIELD: chemistry.

SUBSTANCE: method includes prior concentration of substance during 180 sec with electrolysis potential 2.2 V at device TA-2, as working electrode glass-hydrogen one is used, with following recording of polarization curves at quadratic-wave speed of reaming of potential 50mV/sec and pulse amplitude 11 mV, and concentration of nibentane is determined on basis of pike height in potentials range 0.6-1.4 V relatively to chlorine-silver electrode at background of 0.01 mole/l of potassium chloride with admixture of 0.05 ml of 1% gelatin and 0.45 ml 96% ethanol.

EFFECT: higher sensitivity.

1 ex, 7 tbl

FIELD: chemistry.

SUBSTANCE: rhenium is transferred to solution, it is accumulated on golden-graphite electrode in mixed solution during 90-120 sec with electrolysis potentials (-0.7 ÷--1.0) V relatively to chlorine-silver electrode at background 1M HCl with following recording of anode pikes in executive volt-ampere diagrams filming mode with speed of potential reaming 30-50 mV/sec and concentration is determined on basis of pike height in spectrum of potentials from 0.700 to 0.800 V by method of attested mixtures addition.

EFFECT: higher efficiency.

2 ex, 2 tbl, 1 dwg

FIELD: analytical methods.

SUBSTANCE: invention relates to quantitative determination of substances, which are components of reversible redox systems and consists in titration of a solution to be analyzed including measurement of consumed titrant volume by measuring current intensity using two platinum electrodes with their surface areas being at 1:2 ratio. When measuring current intensity, electrode with greater surface is first used as anode, after which polarity of electrodes is reversed and current intensity is remeasured using as anode electrode with lesser surface. Volume of titrant in end point (Ve.p.) is found from following formula: Ve.p = V(Sc-Sa)(1+i'/i")/(Sc-Sa*i'/i"), where V is volume of titrant solution added, Sa anode surface area, Sc cathode surface area, i' current intensity with greater electrode as anode, and i" current intensity with lesser electrode as anode.

EFFECT: simplified analytical procedure and improved measurement accuracy.

2 dwg, 3 tbl

FIELD: analytical methods.

SUBSTANCE: analytical signals of iodide and iodate ions are simultaneously recorded using direct differential-pulse voltammetry method with potential scanning from -0.15 to -1.55 V against 0.1-0.2 M sodium sulfite solution. Silver electrode or carbon-containing electrode both coated with mercury film, or silver amalgam are utilized as indicator electrode. When determination of iodate ions is not followed by appearance of iodide ion peak in registered voltammetry pattern, formic acid is complementarily added to solution being analyzed and cathodic voltammetry pattern is then registered under the same conditions.

EFFECT: simplified analytical procedure and reduced analysis time.

2 dwg, 2 tbl, 4 ex

FIELD: medicine; chemical engineering.

SUBSTANCE: method involves adding 5 mole/l tartaric acid solution of pH=3.0 to bisubstituted 0.01 mole/l ammonium hydrophosphate solution. The solution is deaerated with oxygen concentration being less than 0.001% during 30 s at (-1.5) V. Electrolysis is carried out during 330 s at (-1.5) V. Gas supply is stopped and current-voltage curve is recorded at voltage scanning rate of 300 mV/s. Standard angiotensin II solution is added, stirred and electrochemical concentrating on is carried out on glass-graphite electrode during 330 s at (-1.5) V. Gas supply is stopped and current-voltage curve is recorded at voltage scanning rate of 300 mV/s. Analytical signal of angiotensin II concentration in potential range of 0.3-0.5 V relative to chlorine-silver electrode.

EFFECT: improved sensitivity and express-analysis features.

4 tbl

FIELD: analytical methods.

SUBSTANCE: invention relates to analytical chemistry focused on environmental objects, such as natural waters, suspended materials of rivers and lacks, soil, bottom sediments, and other solid objects, to measure, in particular, levels of arsenic using voltammeric technique. The latter consists in reduction of all forms of arsenic to arsenic hydride using solution composed of water, 3% sodium hydroxide, and 1.5% sodium borohydride, which solution is added in amount 0.2 ml to 10 ml of liquid analytical sample preliminarily acidified with hydrochloric acid to pH below 2, whereupon, in order to extract arsenic, minor amounts of gold quantitatively comparable with arsenic are added to solution and resulting anolyte is accumulated on the surface of graphite electrode at constant cathode potential -0.4 V for 30 sec using gold as arsine collector. Finally, analytical signal in the form of cathode peak is registered at potential -0.41 V under square-wave voltammetry conditions, which signal is linearly dependent on arsenic concentration in the sample.

EFFECT: enabled monitoring of arsenic concentrations within specified limits and simplified analytical procedure.

1 dwg, 1 tbl

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