VOLTAMMETRIC METHOD FOR SIMULTANEOUS DETECTION OF SELENIUM AND IODINE Russian patent published in 2011 - IPC G01N27/48 

FIELD: chemistry.

SUBSTANCE: voltammetric method for simultaneous detection of selenium and iodine involves alkaline mineralisation of the analysed sample, dissolving the sample mineralisation product in bidistilled water, photoreduction of selenium (VI) ions to selenium (IV) in aqueous solution of the mineralised sample through exposure to UV radiation for 40-60 minutes with addition of sodium hydroxide to pH 8-10, adding aliquots of the exposed solution of the mineralised sample to an electrochemical cell filled with methanoic acid solution and containing a modified indicator silver electrode, a silver chloride comparison electrode, filled with 1 M potassium chloride solution, and a silver chloride auxiliary electrode, bringing the pH of the electrochemical cell to a value between 2.5 and 3.5 through further addition of methanoic acid, exposing the solution of the electrochemical cell to UV radiation for 60 s or less while stirring the solution which is then stopped, and carrying out electrochemical treatment of the modified silver electrode by applying potential of 0.2-0.3 V across the electrode for 2-10 s, resuming stirring and holding the modified silver electrode at potential 0.0 V for 10-60 s, stopping stirring and exposing the solution of the electrochemical cell to UV radiation, more than 5 s long differential pulse scanning of the potential from minus 0.1 V to 1.0 V and recording the iodine current peak in the region of potential from minus 0.35 to 0.45 V and the selenium current peak in the region of potential from minus 0.67 to 0.77 V, simultaneous determination of content of iodine and selenium using standard additives of iodide ions and selenium (IV) ions, added to the electrochemical cell simultaneously.

EFFECT: low consumption of the sample, reagents and shorter analysis time.

2 cl, 3 ex, 3 dwg, 1 tbl