Nano-Composite Carbon Paste Electrode and PVC membrane Sensor for Potentiometric Determination of Erythromycin

In this work, two kinds of potentiometric sensor were introduced. Both sensors respond based on ion-exchange mechanism. Erythromycin-tetraphenyl borate ion-pair was employed as a sensing element in construction of both electrodes. First, PVC membrane electrode was made after series of experiments. The best PVC membrane electrode performance was achieved by a membrane composition of 30% PVC, 60% DBP, and 10% ion-pair. Then, a nano-composite carbon paste electrode was designed to improve the analytical responses. The carbon paste electrode incorporation of multi-walled carbon nano-tube (MWCNTs) and nano-silica showed a better response especially in term of lifetime and response time. The best nano-composite electrode was composed of 25% ion-pair, 4% MWCNTs, 1% nano-silica, 30% paraffin and 40% graphite. The proposed method was successfully applied in determination of erythromycin in some formulations.