Fabrication and characterization of molybdenum(VI) complex-TiO2 nanoparticles modified electrode for the electrocatalytic determination of L-cysteine

A novel voltammetric sensor for the determination of L-cysteine (L-Cys) was fabricated based on a TiO2 nanoparticles/bis[bis(salicylidene-1,4-phenylenediamine) molybdenum(VI)] carbon paste electrode. The electrochemical behavior of the sensor was investigated in detail by cyclic voltammetry. The apparent electron transfer rate constant (k(s)) and charge transfer coefficient (alpha) of the TiO2 nanoparticles/molybdenum(VI) complex/carbon paste electrode (CPE) were also determined by cyclic voltammetry and found to be about 4.53 s(-1) and 0.54, respectively. The sensor displayed good electrocatalytic activity towards the oxidation of L-Cys. The peak potential for the oxidation of L-Cys was lowered by at least 130 mV compared with that obtained at an unmodified CPE. Under optimal conditions, the linear range spans L-Cys concentrations from 1.5x10(-6) to 1.2x10(-3) M and the detection limit was 0.70 +/- 0.01 mu M at a signal-to-noise ratio of 2. In addition, the sensor showed good stability and reproducibility.