Determination of casein by square‐wave voltammetry using electrocatalytic reduction of nickel(II)

The catalytic peak produced at −0.80 V (vs Ag/AgCl) by the presence of casein in the reduction of NIII on a dropping mercury electrode in sodium acetate medium was explored using square-wave voltammetry (SWV). The effects of the electrochemical variables on SW voltammograms were studied and optimum operating conditions were established (10−2 M NiII, 1 M sodium acetate, pH 7.0 and temperature of 23° C). Good linearity between the SW voltammetric peak current and casein concentrations in the 0–128 mg L−1 range was obtained. An electrocatalytic method is proposed for the determination of casein with rapid and precise results (relative standard deviation of 5.2 %).