Determination of sulfamethoxazole in pharmaceutical formulations by flow injection system/HPLC with potentiometric detection using polypyrrole electrode

In this work, it was used a polypyrrole (PPy) electrode as a potentiometric electrochemical detector in a flow injection system in order to determine sulfamethoxazole in pharmaceutical formulations. The PPy electrode was prepared by cyclic voltammetry in acetonitrile solution. A linear relationship was observed over the concentration range of 2.5 × 10-5-1.25 × 10-3 mol L-1 with a correlation coefficient of 0.9977 and limit of detection (LOD) of 1.03 × 10-6 mol L-1 (S/N = 3). The recoveries in tablet and syrup formulations were found as 97.4 and 90.8% with the relative standard deviations of 0.62 and 1.04%, respectively, which closely agree with those measured by high performance liquid chromatography (HPLC) with UV detector. Therefore, it was concluded that the PPy electrode can be used as an alternative novel potentiometric detector material for determination of sulfamethoxazole in pharmaceuticals with the advantages of easy preparation and regeneration capability of the electrode surface

Electroanalytical Determination of Some Sulfonamides on Overoxidized Polypyrrole Electrodes

The electrochemical behaviours of five sulfonamides (sulfanilamide, sulfadiazine, sulfamerazine, sulfamonomethoxine, sulfamethoxazole) were investigated with overoxidized polypyrrole (OPPy) modified pencil graphite electrodes. The performance of the OPPy electrode was evaluated by differential pulse voltammetry in Britton-Robinson buffer solutions prepared in different ratio of acetonitrile-water binary mixture, between pH 1.5 and 7.0. The highest anodic signals of sulfonamides were obtained in Britton-Robinson buffer solution prepared in 50% (v/v) acetonitrile-water at pH 2.5 and 3.0. The OPPy electrodes exhibited good performance for sulfonamides with wide linear ranges (approximate to 10(-5)-10(-3) M), highly reproducible responses (RSD% = 0.9990). The calculated limits of detection were similar to 10(-6) or 10(-7) M at 3 sigma. In order to verify the reliability of the OPPy electrode as a sensor, it is used for determination of sulfamethoxazole in a pharmaceutical tablet. The recovery was found as 95.96% with the RSD% of 0.68. The overoxidized polypyrrole modified pencil graphite electrode showed a stable and reproducible response without any influence of interferent commonly existing in pharmaceutical containing sulfamethoxazole