Voltammetric Determination of Sulfadoxine and Its Application in Pharmaceuticals and Urine Samples

The voltammetric behaviour of Sulfadoxine (SDN) was studied at a glassy carbon electrode in 0.2 M phosphate buffer solutions using cyclic, differential-pulse (DPV) and square wave voltammetry (SWV). The dependence of the current on pH, concentration, and scan rate was investigated to optimize the experimental conditions for the determination of SDN. The oxidation process was shown to be diffusion controlled, irreversible over the pH range from 3.0-9.2. An analytical method was developed for the determination of SDN in phosphate buffer solution at pH 3.0 as a supporting electrolyte. A DPV method showed a good linear response as compared to SWV. The anodic peak current varied linearly with SDN concentration in the range 0.310-4.34 µg ml-1 of SDN with a limit of detection (LOD) of 0.01 µg ml-1. The recovery was determined in the range from 95.6-100.1%. The proposed method was successfully applied to the quantitative determination of SDN in pharmaceutical formulations and an urine as real samples.