Adsorptive stripping voltammetric behaviour and quantification of the tricyclic antidepressant drug doxepin hydrochloride in bulk form, pharmaceutical preparations and biological medium

The electro reductive behaviour of doxepin has been investigated and one irreversible well-defined cathodic peak was observed at -0.62 V vs. Ag/AgCl (3M KCl). The electrochemical reduction and adsorption of doxepin hydrochloride was studied in phosphate buffer medium by cyclic (CV), differential pulse cathodic adsorptive stripping (DP-CAdSV) and square-wave cathodic adsorptive stripping (SW-CAdSV) voltammetric techniques at glassy carbon electrode. The voltammograms showed a single 2-electron irreversible cathodic peak, which may be attributed to reduction of the C=C double bond of the doxepin hydrochloride and the mechanism of reduction was postulated on the basis of controlled potential electrolysis. A fully validated, simple, sensitive and reproducible cathodic adsorptive stripping voltammetric procedure for the trace determination of the doxepin hydrochloride bulk drug in pharmaceutical formulation and in biological medium has been developed. The achieved LOD and LOQ were 4.83 x 10^-6 mL^-1 and 1.5 x 10^-7 mL^-1 by SWCAdSV and 8.9 x 10^-6 mL^-1 and 2.4 x 10^-7 mL^-1 by DPCAdSV respectively. The procedure was applied to the assay of the drug in tablets form with mean percentage recoveries of 100.17% with SWCAdSV and 100.16% with DPCAdSV. Applicability to assay the drug in spiked human urine and serum samples were illustrated and minimum detectability were found to be 2.1 × 10^–7 mol L^–1 and 3.71× 10^–7 mol L^–1 and 3.65 × 10^–7 mol L^–1 and 6.3 × 10^–7 mol L^–1 for DP–CAdSV and SW–CAdSV, respectively. respectively

Author(s): Gopal L. Mourya, Krishna K. Jhankal, Pradeep Parashar and Digish K. Sharma

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