ELECTROCHEMICAL METHOD OF DETERMINING CONCENTRATION OF ARESENIC Russian patent published in 2009 - IPC G01N27/48 

FIELD: chemistry.

SUBSTANCE: present invention pertains to electrochemical methods of determining concentration of arsenic in aqueous solutions and can be used in industry when analysing solutions, in monitoring environmental media, food products as well as other objects, which can be turned into a solution through the corresponding sample preparation. According to the invention, the method involves oxidation of all forms of arsenic to pentavalent arsenic through ozonisation of the analysed solution at pH not less than 8 for 60 seconds. The pentavalent arsenic is then reduced to the electrochemical active form As(III) with UV-irradiation of the solution after adding sodium sulphite (Na₂SO₃) with concentration 0.04 M. Sodium sulphite simultaneously serves as back ground electrolyte and a substance which reacts with dissolved oxygen - barrier when measuring using inversion voltammetry method. Subsequent electrochemical accumulation of arsenic takes place in the same solution at constant potential on a gold-carbon electrode while stirring the solution. Stirring is then stopped and the volt-ampere curve is then plotted, which is the relationship between current of electrochemical dissolution of arsenic and potential in the interval of polarising voltage from minus 0.7 to plus 0.2 V. Concentration of arsenic in the solution is calculated from the graduated curve or using an addition method. The invention seeks to increase rapidness, output, sensitivity of the electrochemical method of determining concentration of arsenic, simplify the sample preparation procedure and subsequent determination using an inversion voltammetry method.

EFFECT: increased rapidness, output, sensitivity of the electrochemical method of determining concentration of arsenic, easier sample preparation procedure and subsequent determination using an inversion voltammetry method.

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