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.

A differential pulse voltammetric sensor for the determination of tamsulosin hydrochloride (TAM) using multiwalled carbon nanotubes (MWNTs)-Nafion-modified glassy carbon electrode (GCE) has been developed. MWNTs were dispersed in water with the help of Nafion and were used to modify the surface of GCE via solvent evaporation. At MWNT-modified electrode, TAM gave a well-defined oxidation peak at a potential of 1084 mV in 0.1 M acetate buffer solution of pH 5. Compared to the bare electrode, the peak current of TAM showed a marked increase and the peak potential showed a negative deviation. The determination conditions, such as the amount of MWNT-Nafion suspension, pH of the supporting electrolyte and scan rate, were optimised. Under optimum conditions, the oxidation peak current was proportional to the concentration of TAM in the range 1 × 10 23 M-3 × 10 27 M with a detection limit of 9.8 × 10 28 M. The developed sensor showed good stability, selectivity and was successfully used for the determination of TAM in pharmaceutical formulations and urine samples.

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