Sensitive Kinetic Spectrophotometric Determination of Copper (II) by Partial Least Squares and Fixed Time Method

A very sensitive and selective kinetic catalytic spectrophotometric method has been developed for the determination of Cu (II). The method is based on the catalytic effect of Cu (II) on the reaction of sulfanilic acid with hydrogen peroxide at pH 6 and 25 °C in aqueous solution. The increase in the absorbance of the reaction mixture at 330nm at a fixed time is proportional to the concentration of Cu (II) over the range of 0.05–6 μg ml–1. Partial least squares modeling as a powerful multivariate statistical tool is also applied and compared for determination of Cu(II) in aqueous solution. The experimental matrix for partial least squares calibration (PLS) method was designed with 14 samples. The cross-validation method was used for selecting the number of factors. The root mean squares error prediction (RMSEP) and the relative error prediction REP(%) were 0.11 and 3.78% respectively. The effects of various cations and anions on Cu (II) determination have been investigated. The capability of the method for the analysis of real sample was evaluated by determination of Cu (II) in serum samples of persons with Wilson disease.