Quantification of Cr(VI)-Thymoquinone Complex Using Cyclic Voltammetry

Abstract

Quantitative studies of Cr(VI)- thymoquinone complex have been performed by cyclic voltammetry. For this purpose glassy carbon, platinum and saturated calomel electrodes were used as working, auxiliary and reference electrodes, respectively. The effects of concentrations and metal-ligand ratios on Cr(VI)- thymoquinone complex were investigated. Effect of concentration was found to follow Randles-Sevcik equation. Calibration curve method with linear regression line confirms that cyclic voltammetry can be used for quantification of Cr(VI)-thymoquinone complex for pharmaceutical assay. Complete complex formation seems to occur at metal ligand ratio 1:1. Results indicate quasi-reversible electron transfermechanism. E° and diffusion coefficient of complex at different concentrations and metal ligand ratios were also calculated and found to be 0.244±0.01 V and 3.45´10-5 cm2s-1, respectively. The values of transfer coefficients, a and b, were found to be 0.716±0.02-1.231±0.01 and 0.814±0.01-0.906±0.01, respectively.