Electrochemical behavior of colchicine using graphite-based screen-printed electrodes

Miniaturized electrochemical graphite based sensor for the analysis of colchicine, along with its detailed construction was described.The electrochemical behavior of colchicine, both by cyclic and differential pulse voltammetry was investigated, showing an irreversible reduction and oxidation mechanism. The effect of several different electrochemical mediators was studied in order to decrease the oxidation potential of colchicine, but none of them showed a favorable electron transfer between the alkaloid and the electrode's surface. The influences of different biomolecules (calf thymus DNA, bovine serum albumin and β-tubulin) over colchicine's electrochemical behavior were also presented.For quantitative determinations the anodic differential pulse voltammetric method in H3PO4/HClO4 0.01 M (pH 2.05) was selected, evaluating one of the oxidation peaks of colchicine at +970 mV versus Ag pseudo-reference. The electrochemical scanning parameters were optimized by an experimental design using response surface modelling. The method was validated according to ICH guidelines in the concentration range 85–1200 ng mL−1 (R2 = 0.9966, n = 7) colchicine in terms of linearity, accuracy, limits of detection (LOD) (41 ng mL−1), limits of quantification (LOQ) and fidelity and it was successfully applied to the determination of colchicine in tablets, without the interference of the excipients.The studied method showed the same sensitivity as the more complex HPLC procedure and micellar electrokinetic chromatography with spectrophotometric detection.