Voltammetric determination of sulfonamides using paste electrodes based on various carbon nanomaterials

The authors have performed a comparative study of the performance of various carbonaceous material-based electrochemical sensors in order to identify the most appropriate sensor for determination of sulfonamides. The electro-oxidative power of carbon paste electrodes prepared using carbon black, graphite, carbon nanopowder, acetylene black, multiwalled carbon nanotubes and glassy carbon powder was investigated by square-wave voltammetry at pH 6.0 using sulfamethoxazole (SMX) as the model analyte. It is found that carbon paste electrodes prepared with graphite or carbon nanopowder and operated at a voltage of 0.93 (vs. Ag/AgCl) display the highest sensitivity and lowest detection limit. Next, the sulfonamides sulfadiazine, sulfacetamide, sulfadimethoxine, sulfathiazole, sulfamethiazole and sulfamerazine were also tested. The voltammetric response is linear in the 1 to 75 μM concentrations range, with detection limits range from 0.4 to 1.2 μM, and sensitivities were between 10 and 38 nA⋅μM−1. The carbon nanopowder paste electrode (CNPE) showed the lowest detection limit (0.12 μM) for SMX and was successfully applied to its determination in (spiked) water samples and in pharmaceutical formulation.