Simultaneous kinetic spectrophotometric determination of five phenolic compounds by reaction with p-aminophenol, using partial least squares data treatment

Abstract

A fast and accurate procedure has been developed for the simultaneous determination of resorcinol, m-aminophenol, o-cresol, phenol and m-cresol in waters. The method is based on the reaction between the aforementioned phenolic compounds, at concentration levels of ppm, and 300 ppm of p-aminophenol in 0.05 mol l^–1 NaOH and in the presence of 0.004 mol l^–1 KIO₄. The treatment of absorbance data, between 400 and 700 nm, obtained at interval times of 20 s between 40 and 120 s and 40 s between 120 and 600 s, by means of the use of Partial Least Squares 2 (PLS-2), using the UNSCRAMBLER program, suggested that the use of 7 factors can explain more than 99.5% of the residual variance. The method has been applied to the analysis of synthetic samples, not employed for calibration, and average errors lower than 4% were found.