POLAROGRAPHIC-BEHAVIOR OF SULFADIAZINE, SULFAMERAZINE, SULFAMETHAZINEAND THEIR MIXTURES - USE OF PARTIAL LEAST-SQUARES IN THE RESOLUTION OF THE NONADDITIVE SIGNALS OF THESE COMPOUNDS

The polarographic behaviour of the sulfonamides sulfadiazine, sulfamer azine and sulfamethazine was studied in Britton-Robinson buffer soluti ons, These compounds show well defined reduction waves and differentia ted peaks in differential-pulse polarography (DPP) with E(p) values ne ar -700, -790 and -1140 mV, respectively, in an acidic medium (approxi mately pH 2), the behaviour of the sulfonamides in response to variati ons in pH and concentration is very similar, However, when two or thre e of these compounds are present together, the signal obtained in DPP does not agree with the superposition of the signal of each one of the m when present alone. This fact can be explained by the. change that t he de wave corresponding to any of the sulfonamides undergoes owing to the presence of one or two of the others, thus making the direct anal ysis of their mixtures by DPP impossible, The ability of partial least squares multivariate methods to resolve this problem was examined. In general, good results were obtained and the method was applied to the analysis of mixtures of these sulfonamides in veterinary and pharmace utical formulations.