FIELD: chemistry.;SUBSTANCE: method of determining cysteine in aqueous solutions via cyclic voltammetry on a graphite electrode modified by colloidal gold particles according to the invention involves concentration of an electroactive compound on the surface of the electrode and obtaining an analytical signal by measuring potential, wherein the graphite electrodes are modified by colloidal gold particles, followed by detection of inverse peaks of electrooxidation of cysteine on the cathodic curve with potential sweep rate of 100 mV/s on a 0.1 M NaOH background solution; concentration of cysteien is determined from the value of maxima of current versus voltage curves in the potential range from minus 0.20 V to plus 0.10 V relative a saturated silver chloride electrode via a certified mixture addition technique.;EFFECT: more sensitive method of determining cysteine in aqueous solutions via cyclic voltammetry.;2 ex, 2 tbl, 2 dwg
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