COMPARATIVE CHARACTERISTICS OF COATINGS ELECTROPOLYMERIZED FROM AQUEOUS MEDIA AND DEEP EUTECTIC SOLVENTS AND THEIR USING IN POTENTIOMETRIC SENSORS

Comparative investigation of potentiometric characteristics was carried out for coatings electropolymerized from phosphate buffer and HEPES buffer solutions or deep eutectic solvents, such as reline and mixture of citric acid, glucose and water. Both the effect of media acidity on sensor potential and the potentiometric response reversibility were evaluated for all the coatings synthesized. The solid contact potentiometric sensor array was developed for the determination of easily oxidizing organic compounds: hydroquinone, dopamine, quercetin and ascorbic acid. Analytical characteristics of such easily oxidizing organic compounds determination were established. According to the media pH the analytes can perform as either single-charged ions demonstrating the slopes close to Nernstian values or reducing agents influencing on polymer redox forms ratio in modifying coating. The coatings synthesized from deep eutectic solvents showed a wider linear range of determined concentrations. Also, they had better sensitivity comparing with those electrodeposited from aqueous media. The solid contact potentiometric sensors were tested for analytes determination in real samples of cosmetics, pharmaceuticals and biologically active additives with 92–107% recovery.