Selective determination of cysteine in the presence of tryptophan by carbon paste electrode modified with quinizarine

摘要: A sensitive and selective electrochemical method for the determination of L-cysteine was developed using a modified carbon paste electrode (MCPE) with quinizarine. Cyclic voltammetry used to investigate redox properties this at various solution pH values scan rates. The apparent charge transfer rate constant, ks coefficient electron between quinizarine (CPE) were calculated as 2.76 s−1 0.6, respectively. This shows excellent electrocatalytic activity toward oxidation in phosphate buffer (pH 7.0). linear range 1.0 × 10−6 10−3 M detection limit (3s) 2.2 10−7 observed 7.0 solutions. In differential pulse voltammetry, (QMCPE) could separate peak potentials tryptophan present same solution, though unmodified CPE indistinguishable. work introduces simple easy approach presence tryptophan. Also, employed real samples such serum blood acetylcysteine tablet.