Differential pulse voltammetric determination and catalytic oxidation of sulfamethoxazole using [5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrinato] Cu (II) modified carbon paste sensor

Sulfamethoxazole (SM) is a sulfonamide bacteriostatic antibiotic. Its primary activity is against susceptible forms of streptococcus, staphylococcus aureus, escherichia coli, haemophilus influenzae, and oral anaerobes. It is commonly used to treat urinary tract infections. In addition it can be used as an alternative to amoxicillin-based antibiotics to treat sinusitis. It can also be used to treat toxoplasmosis. In the present work, a metalloporphyrin modified carbon paste sensor was fabricated and the electrochemical behaviour of SM was studied using differential pulse voltammetry (DPV). Cu (II) complex of 5,10,15,20-tetrakis (3-methoxy-4-hydroxy phenyl) porphyrin (TMHPP Cu (II)) was used as the active material. Compared with bare carbon paste electrode (CPE), the TMHPP Cu (II) modified CPE exhibits excellent enhancement effect on the electrochemical oxidation of SM. A well-defined oxidation peak of SM occurs at -140 mV in 0.1M phosphate buffer solution (PBS) of pH 6. All the experimental parameters were optimized and it was found that under optimum conditions the oxidation peak current was linear to the concentration of SM in the range of 1.0 x 10(-2)-1.0 x 10(-8) M with a detection limit of 1.5 x 10(-9)M. The developed sensor has been successfully applied for the determination of SM in pharmaceutical formulations and urine sample. Copyright (C) 2010 John Wiley & Sons, Ltd.