Application of H-Point standard addition method and multivariate calibration methods to the simultaneous kinetic-potentiometric determination of permanganate and dichromate

Abstract

Simultaneous kinetic-potentiometric determination of binary mixture of permanganate (MnO4−) and dichromate (Cr2O72−) by H-point standard addition method (HPSAM), partial least squares (PLS) and principal component regression (PCR) is described. In this work, the difference between the rate of the oxidation reaction of Fe(II) to Fe(III) in the presence of MnO4− and Cr2O72− formed the basis of the method. The rate of the consumed fluoride ion for making the complex was detected by a fluoride ion selective electrode (FISE). The results show that the simultaneous determination of MnO4− and Cr2O72− could be conducted in their concentration ranges of 0.5–10.0 and 0.1–20.0 μg ml−1, respectively. The total relative standard error (RSE) for applying the PLS and PCR methods to 9 synthetic samples was 5.30 and 3.17, respectively in the concentration range of MnO4−, and 3.30 and 2.04, respectively, in the concentration range of Cr2O72−. In order for the selectivity of the method to be assessed, we evaluated the effects of certain foreign ions upon the reaction rate. The proposed methods (HPSAM, PLS and PCR) were evaluated using a set of synthetic sample mixtures and then applied to the simultaneous determination of MnO4− and Cr2O72− in different water samples.