Voltammetric determination of sulfamethoxazole at a multiwalled carbon nanotube modified glassy carbon sensor and its application studies

Sulfamethoxazole (SMX) is an anti-bacterial sulfonamide. It prevents the formation of dihydrofolic acid, a compound that bacteria need in order to survive. The present work details the voltammetric analysis of SMX at a multiwalled carbon nanotube (MWCNT)-Nafion modified glassy carbon electrode (GCE). Sulfamethoxazole gives a well defined oxidation peak at 0.74 V in 0.1 M phosphate buffer solution (PBS) of pH 8.0. The experimental parameters such as the amount of MWCNT-Nafion suspension, the pH of the supporting electrolyte and scan rate were optimized and a direct electrochemical method for the determination of SMX was developed. Under optimum conditions the oxidation peak current is linear to the concentration of SMX in the range 1 x 10(-2) - 5 x 10(-5) M with a detection limit of 1 x 10(-5) M. The MWCNT/GCE showed good stability, selectivity and was successfully used to quantify SMX in pharmaceutical formulations and urine sample.