Determination of Copper(II) Ions by Diffuse Reflectance Spectroscopy Method

Abstract

A method for copper(II) determination based on copper(II) ions interaction with the organic reagent picramine-ε, concentrating the formed complex on a solid-phase matrix and recording diffuse reflectance spectroscopy spectra by a portable combined LED miniphotometer was developed. Poly-ε-caproamide membranes were investigated as solid-phase matrixes. It was found that the diffuse reflectance coefficient of the studied membranes in the visible spectrum region does not depend on wavelength. So, the signal from membranes does not distort the results of the analysis. Factors controlling the process of sorption of the copper(II) complex with picramine-ε were studied. It was shown that the poly-ε-caproamide membranes are effective sorbents which provide the possibility of concentrating the analyte at a level higher than 105. The dependences of analytical signal on the acidity of the solution, the time of keeping the complex in the solution and the initial volume of the solution passed through the membrane were studied. Based on the obtained data, the optimal conditions of the analysis were found. Calibration dependence of the analytical signal on the concentration of copper(II) in model solutions was estimated. The method was tested for the determination of copper(II) ions in white wine. The method of additives was used for the analysis. It was found that the concentration of copper(II) ions in “Vagrus” wine is 0.0016 mkg/ml.