Polarographic and voltammetric assays of sulfonamides as alpha-oxo-gamma-butyrolactone arylhydrazones

2-Acetylbutyrolactone was characterized as a novel reagent of analytical potential in polarographic and voltammetric analyses. It forms alpha-oxo-gamma-butyrolactone arylhydrazones through Japp-Klingemann coupling reaction with primary arylamines. alpha-Oxo-gamma-butyrolactone arylhydrazones possess an electro-active site ( azomethine center) that displays a cathodic activity at the mercury electrode. The protonated azomethine center of alpha-oxo-gamma-butyrolactone arylhydrazones is reduced by 2e/2H(+) reaction to the hydrazo form. The differential pulse polarographic behavior of alpha-oxo-beta-butyrolactone arylhydrazones was investigated in aqueous media ranging from pH 2 to 10.5. In aqueous acidic solution, alpha-oxo-gamma-butyrolactone arylhydrazones were shown to adsorb on a hanging mercury drop electrode and to be amenable to determination by adsorptive stripping voltammetry. Procedures for applying the polarographic and voltammetric methods to determination of sulfadiazine and sulfamethoxazole in pharmaceutical preparations have been developed. An analogous study on sulfas-azo derivatives of ethyl acetoacetate was also considered. Furthermore, the differential pulse voltammetric method was adopted for determination of sulfamethoxazole in spiked plasma and urine samples. The recoveries turned out to be satisfactory, showing relative standard deviations from 2.4 to 4.6%.