Electroanalysis of ascorbic acid using poly(bromocresol purple) film modified glassy carbon electrode

We report a simple method for determination of ascorbic acid (AA) by using a glassy carbon electrode (GCE) modified with poly(bromocresol purple) (poly(BCP)/GCE). Compared with a bare GCE, the poly(BCP) film exhibited the obvious electrocatalytic effect towards ascorbic acid oxidation, which reduced the oxidation overpotential about 240 mV with obviously increased current response. Under the optimized conditions, the catalytic current increased linearly with the concentration of AA in the range of 2.0 x 10(-5)-7.0 x 10(-4) M with the detection limit of 6.5 x 10(-6) M (S/N = 3) in 0.1 M phosphate buffer solution (pH 6.5). The interferences from different species and the repeatability of the poly(BCP)/GCE for the determination of AA were also investigated. The proposed method has been successfully applied to the determination of AA in vitamin C injection and tablet with satisfactory results. (C) 2012 Elsevier Ltd. All rights reserved.