Abstract

In this work, a new version of RAFA was developed for simultaneous determination of the stepwise dissociation constants along with concentration of multiprotic acids based on pH gradual change-UV spectral data. The main aim of this study was to introduce an improved version of the model based RAFA for quantification of analytes and also calculation of model parameters without knowing the pure spectra. The proposed method was validated by analyzing simulated data at the first stage. Then, the binary mixtures of ascorbic and sorbic acids were selected as the model compounds and good analytical results were obtained using the proposed procedure. Finally, the method was successfully applied to simultaneous determination of ascorbic acid and sorbic acid in sour cherry juice as a real sample.

Keywords: Ascorbic acid, chemical equilibrium model, pH-spectra, polyprotic acids, rank annihilation factor analysis, sorbic acid.

Graphical Abstract