Modified pencil graphite electrode as a novel electrochemical sensor for the determination of paroxetine

Paroxetine (PRX) is a selective serotonin reuptake inhibitor, with antidepressant and anxiolytic activity [1]. To date various analytical methods have been developed for the determination of paroxetine such as chromatography [2], spectroscopy [3] and electrochemistry [4]. Among these, chromatographic methods are most commonly used, while non-chromatographic direct methods are rare. Compared to other determination techniques, electroanalysis has the advantages of simplicity, high sensitivity and in most cases , selectivity. In this work, An electrochemical sensor was developed for determination of paroxetine using a physical pretreated and electrochemical modified pencil graphite electrode(PGE). Pretreatment of the electrode was done by placing the PGE in a stirring sulfuric acid solution for an hour at 80oC. Modification of the pretreated pencil graphite electrode (PPGE) was then performed by the reduced graphene oxide-phosphotungstic acid (RGO-PTA) with potentiostatic procedure at -1.2 V for 5 min in 0.1 M phosphate buffer solution of pH=7. Surface morphology of the modified PGE was analyzed with SEM, FT-IR and electrochemical impedance spectroscopy (EIS) techniques while the electrochemical studies were done. The kinetic parameter charge transfer coefficient, α, was determined for oxidation of PRX at modified PPGE. In optimum experimental conditions, differential pulse voltammetry (DPV) was used for determination of PRX, which exhibits a linear calibration graph of Ip versus PRX concentration in the range of 15-3.3×104 nM with a correlation coefficient of 0.999. The calculated detection limit was obtaind equal to 8 nM. Modified PPGE was successfully used for determination of PRX in paroxetine tablets and biological samples such as human serum and urine samppels.