Indirect measurement of cephalosporins and penicillins by differential pulse adsorptive stripping voltammetry at mercury electrode

Abstract

In order to determine certain β-lactam antibiotics at trace level, a differential pulse adsorptive stripping voltammetric (DPAdSV) method has been suggested. The model cephalosporin, viz., cefaclor, was transformed into the corresponding electroactive oxazolone derivative under drastic acid treatment. It was then subjected to the adsorptive accumulation onto a hanging mercury drop electrode [accumulation potential -0.1 V vs. Ag/AgCl, accumulation time 60 s, 40% ethanolic buffer (pH ≃ 8, I = 0.1 mol L-1)] for DPAdSV measurement. The detection limit for cefaclor was as low as ppb level (≥4 ng mL-1, S/N = 3, RSD = 2.9%, n = 5) at an accumulation time of 60 s. The method was found to be useful for the quantitative analysis of cefaclor, ampicillin and amoxycillin at trace levels, and extended to the analysis in their pharmaceutical preparations.