Applications of carbon based electrodes for voltammetric determination of lornoxicam in pharmaceutical dosage form and human serum.

A simple, reliable and selective differential pulse (DP) and square wave (SW) voltammetric methods at glassy carbon (GC) and boron-doped diamond (BDD) electrodes of lornoxicam in pharmaceutical dosage form and in spiked human serum samples have been developed and evaluated. The possible oxidation mechanism was discussed. The voltammetric study of the model compounds allowed elucidating the possible oxidation mechanism of lornoxicam. The dependence of the peak current and peak potentials on pH, concentration, nature of the buffer, and scan rate were investigated. The oxidation of lornoxicam gave a single and irreversible peak at both electrodes. The process was found diffusion controlled. For glassy carbon electrode, the linearity of the calibration curve was obtained in range of 4x10-7 M to 2x10-5 M for DPV method and 4x10-7 M to 4x10-5 M for SWV method in 0,1 M sulphuric acid solutions. Using boron-doped diamond electrode, the plot of the calibration curve was linear between 6x10-7 M and 1x10-4 M for both voltammetric methods in pH 2 BR buffer. The repeatability, reproducibility, precision and accuracy of the proposed methods were investigated.