Voltammetric Electrochemical Behavior of Carbon Paste Electrode Containing Intrinsic Silver for Determination of Cysteine

In this paper, the electrochemical behavior of cysteine is described, using carbon paste electrodes (CPEs) modified with ternary silver-copper sulfide containing intrinsic silver at two pH values (pH 3 and 5). Experiments have revealed that presence has a large impact on CPEs. Observed phenomena take place in solution, as well surface CPEs, can be applied for electroanalytical purposes. Based observed examined system, differential pulse voltammetry (DPV) was selected an method determination cysteine. The effects various parameters signal, such amount electroactive material, parameters, etc., were investigated voltammograms. results indicated signal characterized well-defined cathodic peak 0.055 V vs. Ag/AgCl (3 M) acetic buffer solution 5 used indirect optimization procedure most sensitive stabile electrode 5% modifier. DPV response electrode, cysteine, showed different linear concentration ranges 0.1 to 2.5 ?M, 5.6 28 ?M. explanation origin proposed. lower range by remarkable sensitivity 11.78 ?A ?M?1, owing chosen determination. calculated limit detection (LOD), quantification (LOQ) 0.032 0.081 respectively. influence interfering agents examined, low or no interference DPVs observed. proposed validated pharmaceutical preparations satisfactory recoveries 97 101.7%.