Portugaliae Electrochimica Acta 2009, 27(6), 645-655 DOI: 10.4152/pea.200906645 PORTUGALIAE ELECTROCHIMICA ACTA ISSN 1647-1571 A Study of Stripping Voltammetric Behaviour of Cefadroxil Antibiotic in the Presence of Cu (II) and its Determination in Pharmaceutical Formulation Ahmad H. Alghamdi, 1,* Ali F. Alghamdi, 2 Mohammed A. Alomar 3 1 Department of Chemistry, College of Science 2 Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, P.O Box 2455, Riyadh- 11451, Saudi Arabia 3 Department of Chemistry, College of Science,Taibah University, P.O Box 30100, Madinah City, Saudi Arabia Received 11 November 2008; accepted 10 September 2009 Abstract Square-wave voltammetry was used to explore the adsorption property of cefadroxil complex with copper ions on the hanging mercury drop electrode (HMDE). By employing the adsorptive stripping voltammetric approach, a sensitive electroanalytical method for the quantitative analysis of cefadroxil antibiotic was achieved. A well- developed voltammetric peak was obtained in pH 10 Britton-Robinson buffer (B-R buffer) at -650 mV. The cyclic voltammetric studies indicated that the reduction process was irreversible and primarily controlled by adsorption. An investigation of the variation of adsorptive voltammetric peak current with supporting electrolyte, pH, accumulation time, accumulation potential, scan rate, pulse amplitude, SW frequency, working electrode area and convection rate has resulted in the recognition of optimal experimental conditions for cefadroxil analysis. The studied electroanalytical signal showed a linear response for cefadroxil in the concentration range 6×10 -7 - 2×10 -6 mol L -1 (r = 0.999). A limit of detection of 2×10 -9 mol L -1 with relative standard deviation of 2.783 RSD% and mean recovery of 99% was obtained. Possible interferences by several substances usually present in pharmaceutical formulation were also evaluated. The analytical quantification of cefadroxil in commercially available pharmaceutical formulation was performed and compared with data from HPLC technique. Keywords: adsorptive stripping voltammetry, square wave voltammetry, cefadroxil antibiotic, drug-metal ions complex. * Corresponding author. E-mail address: ahalgamdy@gmail.com