Two charge-transfer complex spectrophotometric methods for the determination of sulpiride in pharmaceutical formulations

Two simple, rapid, accurate and sensitive spectrophotometric methods are described for the determination of sulpiride. They are based on charge transfer complexation between the drug as n-electron donor and p-chloranilic acid as pi acceptor or iodine as sigma-acceptor. These give highly coloured complexes with absorption maxima at 518 and 363, 294 nm, respectively. Beer's law linear ranges were 13.7-341.4 and 1.7-20.5 A mu g mL(-1) for the p-chloranilic acid and iodine methods. The methods were successfully applied to the determination of the drug in DogmatilA (R) Fort tablets and the results compared with the official method. The complex association constants and standard free energy changes were calculated using Benesi-Hildebrand plots.