Clavulanate-selective electrodes – application to pharmaceutical formulations

Abstract.

The construction and assessment of a clavulanate anion-selective electrode and its application to the analysis of pharmaceutical formulations by direct potentiometry are described. The electrode, prepared without inner reference solution, was fabricated by use of a PVC membrane, with bis(triphenylphosphoranylidene)ammonium clavulanate as ion-exchanger dissolved in 2-nitrophenyl octyl ether as intermediate solvent and p-t-octylphenol as additive. The response of the electrode was linearly dependent on concentration within the range 2.4×10^–3–1×10^–1 mol dm^–3 (ionic strength adjusted to 0.1 mol dm^–3); the slope of the calibration plot was –59.4±0.9 mV  decade^–1 and the reproducibility ±0.6 mV day^–1. The response time was less than 20 s. Relative errors were <3.5% when results from analysis by direct potentiometry were compared with those from the reference method.