Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
182043 | Electrochemistry Communications | 2008 | 4 Pages |
The determination of cysteine by means of square wave cathodic stripping voltammetry (SWCSV) is reported here for the first time at Bi-modified carbon paste electrodes (CPEs). The modified electrodes are 17% w/w metallic Bi powder mixed with CP (Bi-CPEs) and the technique is based on the enhancement of Bi surface oxidation in the presence of cysteine at a carefully chosen accumulation potential and the subsequent reduction-stripping of the product (proposed to be bismuth(III) cysteinate) by potential scanning to more negative values. The wide concentration range of 1 × 10−6–5 × 10−5 M for cysteine can be assessed by SWCSV using Bi-CPEs and, by appropriate choice of accumulation times, two linear response concentration regimes could be identified: 1 × 10−6–1 × 10−5 M (accumulation for 600 s) and 1 × 10−5–5 × 10−5 M (accumulation for 100 s), with estimated detection limits of 3 × 10−7 and 2 × 10−6 M, respectively.