Method validation in quantitative electrochemical analysis of colchicine using glassy carbon electrode

摘要

A cathodic differential pulse voltammetric determination of colchicine was validated using a glassy carbon electrode in HClO4/H3PO4 0.01 M.Colchicine gives an irreversible,di?usion-controlled peak at -862 mV vs.Ag/AgCl reference electrode.The cathodic peak is strongly influenced by a more alkaline environment with a shift towards more negative potentials.Method optimization was carried out in parallel for three types of electrodes(glassy carbon,mercury film and bismuth film coated glassy carbon).The cathodic peak current is higher using film-coated electrodes,but shows poorer intra-day reproducibility and a longer analysis time due to film renewal.Thus,a bare glassy carbon electrode was used to determine colchicine in the concentration range of 2.4-50 mu g mL~(-1)(R~2=0.9998,n=5), with a calculated detection limit of 0.80 mu g mL~(-1).The proposed method was characterized according to ICH Harmonized Tripartite Guidance Q2(R1)by validation parameters(selectivity,linearity,accuracy, fidelity,limit of detection,limit of quantification)and it was successfully applied for the determination of colchicine from tablets,without the interference of the excipients.The method's performances were evaluated and compared with both a known polarographic method and the official quantitative spectrophotometric determination from the Romanian Pharmacopoeia,Xth edition,respectively.