Application of Polymer‐Modified Hanging Mercury Drop Electrode in the Indirect Determination of Certain β‐Lactam Antibiotics by Differential Pulse, Ion‐Exchange Voltammetry

A selective and sensitive polymer-modified electrode was developed for β-lactam antibiotics (cefaclor, amoxycillin and ampicillin) present in formulated and blood plasma samples for the quantitative analysis in aqueous environment. The detection was made using an ion-exchange voltammetric technique, in differential pulse mode, on poly(N-chloranil N,N,N′,N′-tetramethylethylene diammonium dichloride)-modified hanging mercury drop electrode of a three-electrode system (PAR Model 303A) attached with a Polarographic Analyzer/Stripping Voltammeter (PAR Model 264A). Antibiotics, which are electroinactive compounds, were essentially converted to their electroactive oxazolone analogues through acid treatment under drastic conditions (0.1 mol L−1 HCl, ∼85 °C, 2 h). These analytes in the form of their respective oxazolones were indirectly analyzed by oxazolone entrapment in the polymeric film through ion-exchange process at modified electrode surface (accumulation potential −0.20 V (vs. Ag/AgCl), accumulation time 120 s, pH 7.4, KH2PO4-NaOH buffer (ionic strength 0.1 mol L−1), scan rate 10 mV s−1, pulse amplitude 25 mV). The limit of detection of cefaclor-derived oxazolone was found to be 2.12 nmol L−1 (0.82 ppb, S/N 3, RSD 3.21%) in terms of cefaclor (a representative β-lactam) concentration.