Potentiometric PVC Membrane Sensor for the Determination of Phenylephrine Hydrochloride in Some Pharmaceutical Products

A new PVC membrane electrode for the determination of phenylephrine hydrochloride based on the formation of an ionassociation complex of phenylephrine hydrochloride with the phosphotungstate counter anion as an electroactive material dispersed in a PVC matrix is described. The sensor shows a fast, stable, near-Nernstian response for 1.0 × 10-5 to 1.0 × 10-1 M phenylephrine hydrochloride at 25 °C over the pH range of 3.5-8.0 with a cationic slope of 58.1 ± 0.6 mV decade-1. The electrode was successfully used for potentiometric determination of phenylephrine hydrochloride in some pharmaceutical drugs