New way of application of the bromate–bromide mixture in kinetic analysis Original Research Article

The bromine generated in situ by the bromate–bromide mixture has usually been used in kinetic analysis to determine either individual species that give reaction with bromine or the total concentration of mixtures of those analytes. In this paper the bromate–bromide mixture is proposed as a reagent for multicomponent kinetic determinations. Mixtures of acetylsalicylic acid (ASA) and paracetamol (AAP) have been used to test the discriminating ability of reactions with bromine. The reaction between bromine and AAP is fast and the reaction between bromine and ASA is negligible. However, ASA slowly hydrolyzes to yield salicylic acid (SA) and acetic acid, and the reaction between bromine and SA can be considered fast in the reaction conditions. This complex behaviour contains enough information to resolve mixtures of ASA and AAP after applying partial least squares regression (PLS) to the kinetic photometric data. After optimization, errors around 5–6% were found for the determination of ASA and AAP. Quimiometric considerations on the calibration models are made. The method has been successfully applied to the determination of ASA and AAP in pharmaceuticals.