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

- Conducting polymers are predicted to possess outstanding mechanical, electrical and thermal properties. It is for this reason that they have been targeted for many potential applications.
- Conducting polymers modified electrodes have been successfully developed for electrooxidation of 2-thiouracil (2TU) in phosphate buffer solution. Conducting polymers showed electrocatalytic action for the oxidation of 2TU, characterizing by the enhancement of the peak current, which was probably due to the large surface area of modified electrodes.
- The atomic force microscopy was applied to characterize the surface morphology of modified electrode.
- This sensor can be used for voltammetric determination of selected analyte as low as 1.3 nM with good reproducibility. The modified electrode has been used to determine 2TU in pharmaceutical and human biological samples.
- The proposed method offered the advantage of accuracy and time saving as well as simplicity of reagents and apparatus.

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. 0.1 mM 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 × 10−7 M for PP/GPE with a detection limit of 1.6 × 10−9 M and 1.0 × 10−8 − 1.3 × 10−7 M for PA/GPE with a detection limit of 1.8 × 10−9 M. The sensors were successfully applied to determine the trace amounts of 2TU in human biological fluids and pharmaceutical samples.