Voltammetric Determination of Meloxicam in Pharmaceutical Formulation and Human Serum at Glassy Carbon Electrode Modified by Cysteic Acid Formed by Electrochemical Oxidation of L-cysteine

摘要

The improvement of electrochemical detection of meloxicam is presented by modification of a glassy carbon electrode with anionic layer of cysteic acid providing electrostatic accumulation of the analyte onto the electrode surface. The modification formed by electrochemical oxidation of L-cysteine was performed by cycling potential in cysteine solution. The anodic peak current obtained at + 1.088 V (vs. Ag/AgCl) by voltammetry was linearly dependent on the meloxicam concentration in the range of 4.3 × 10-8 ~ 8.5 × 10-6 M in the B-R buffer solution (0.04 M, pH 1.86) with a correlation coefficient of 0.999. The detection limit (S/N = 3) is 1.5 × 10-9 M. The low-cost modified electrode shows good sensitivity, selectivity and stability and has been applied to the determination of meloxicam in pharmaceutical formulation and spiked serum with satisfactory results. The electrochemical reaction mechanism of meloxicam was discussed.