Staircase voltammetric determination of 2-thiouracil in pharmaceuticals and human biological fluids at polyaniline and polypyrrole film modified sensors

Abstract

The conducting polymers like polyaniline(PA) and polypyrrole (PP) films modified graphite pencil electrodes (GPE) were used to determine the trace amounts of 2-thiouracil (2TU) in biological samples using cyclic and stair case voltammetric techniques. 0.1mM each of aniline and pyrrole were successfully electropolymerized separately on GPE using cyclic voltammetry. Morphology of electrodes was characterized by AFM. The negative shift of oxidation potential compared to bare GPE, shows that the PA and PP modified electrodes had catalytic activity for the 2TU oxidation. The results showed that the electrochemical oxidation of 2TU on the modified electrodes was diffusion-controlled. The effects of pH, scan rate, concentration of 2TU and modifiers were optimized. Under optimized conditions, the electrodes showed a linear response in the range of 1.0×10−8 − 1.5×10−7M for PP/GPE with a detection limit of 1.6×10−9M and 1.0×10−8 − 1.3×10−7M for PA/GPE with a detection limit of 1.8×10−9M. The sensors were successfully applied to determine the trace amounts of 2TU in human biological fluids and pharmaceutical samples.