The voltammetric study of 2-mercapto-5-phenylammino-1,3,4-thiadiazole using carbon paste electrodes

A rapid and accurate voltammetric method for the quantitative determination of 2-mercapto-5-phenylammino-1,3,4-thiadiazole (MPATD) with carbon paste e lectrodes (CPE) has been developed. The study was made by cyclic voltammetr y between -0.4 and +0.6 V with 50 mV s(-1) sweep rate in aqueous solution. After successive oxidation/reduction cycles we found a total oxidation of M PATD at + 0.45 V, As the compound is oxidated, the reduction current peak i ncreases at + 0.13 V, indicating an irreversible process. Following only th e oxidation process in the - 0.1 to + 0.6 V range, we investigated the opti mum scan rates at different current densities and pH values (realised with buffers, pH between 1.0 and 10.0) with CPE versus Ag/AgCl reference electro de using linear sweep voltammetry. We found a good linear relation between the current peak height and concentration in a 2.5.10(-9)-1.25.10(-7) mol m l(-1). This method allows the quantitative detection of the MPATD as it or from dosage forms and biological media. (C) 1998 Elsevier Science B.V. All rights reserved.