Determination of trace amounts of Cu(II) in drinking and wastewater samples by a novel catalytic kinetic spectrophotometric method

Abstract

The current method is based on the catalytic effect of Cu(II) on the oxidation of xylidyl blue (XB) by hydrogen peroxide (H 2O 2) in pH 10.5 borate buffer medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of XB at 570 nm. The optimum operating conditions regarding concentration of reagents, pH and temperature were studied and optimized in detail. A fixed time method was used for processing kinetic data. The working curve is linear in the concentration range of 2.5 to 75 ?g L - 1 of Cu(II). The maximum percentage error and relative standard deviation (RSD) for the determination of Cu(II) in the range of 2.5 to 75 ?g L - 1 have been calculated to be 3.6% and 0.5%, respectively. The detection limit and quantification limit were calculated statistically as 0.85 and 2.58 ?g L - 1, respectively. The effect of possible interfering species was also investigated in real samples. The developed procedure was successfully applied to the determination of Cu(II) in different water samples such as tap water, drinking water and wastewater. Evaluation of the accuracy of the proposed kinetic method by using a certified environmental water sample (SRM 1640) was verified with the application of an alternative analytical technique such as ICP-AES (inductively coupled plasma atomic emission spectroscopy) and the obtained data were compared with those obtained by the presented kinetic method. It was found that the results of copper determination are statistically in agreement with its certified value and are comparable with those obtained by means of ICP-AES. © 2012 Copyright Taylor and Francis Group, LLC.