Selective and sensitive determination of tinidazole in pharmaceuticals and biological matrix using poly(diphenylamine -4- sulfonic acid) modified glassy carbon electrode

Abstract

Antibiotics have been effectively used in the last decades to prevent bacterial infections in humans and animals. In this study an electrochemical sensor based on poly(diphenylamine sulfonic acid) (poly(DPASA)) modified glassy carbon electrode was prepared by electropolymerization of 1.0 mM DPASA in 0.1 M KCl in the potential window of −1.2 to +1.80 V for 20 cycles and characterized using cyclic voltammetry and electrochemical impedance spectroscopy using [Fe(CN)6]3−/4-. In contrast to GCE, the poly(DPASA)/GCE showed catalytic activity towards the reduction of tinidazole, which attributed to increase in its surface area. A good linear relationship between the reductive peak current and square root of scan rate indicated that tinidazole reduction at poly(DPASA)/GCE was diffusion controlled process. The peak current response of tinidazole reduction at the poly(DPASA)/GCE was linearly related with its concentration ranged from 0.05 to 300 μM with detection limit and quantification of 0.00427 μM and 0.0142 μM, respectively. The tinidazole content of drug samples claimed 300 mg/tablet in three tablets (China, Cyprus, and India) were detected in the range 96% (Cyprus 20) to 101.78% (India 40) of the expected with %RSD value below 2.0%. The poly(DPASA)/GCE was successfully applied for tinidazole detection in drugs and urine samples, where recovery between 96.0 and 101.78% and 98.45 to 101.11% were obtained, respectively. The selectivity of poly(DPASA)/GCE was evaluated in the presence of amoxicillin, ciprofloxacin, paracetamol, glucose and uric acid in drug samples and there were no significant change in the current response of tinidazole, indicated the excellent selectivity of the poly(DPASA)/GCE.