Spectrophotometric simultaneous determination of nickel, cobalt and copper by orthogonal signal correction–partial least squares

Abstract

A method for the simultaneous spectrophotometric determination of nickel, cobalt and copper based on the<br />formation of their complexes with 2-(2-Thiazolylazo)-p-Cresol (TAC) in micellar media of Triton X-100 is<br />proposed. The absorbance spectra were recorded in the range of 500 to 800 nm. The linear concentration<br />range for nickel, cobalt and copper in solution calibration sets were 0.05–1.80, 0.10–6.41 and 0.10–6.54<br />μg/ml, respectively. The effects of experimental parameters such as pH, time, concentration of ligand and<br />surfactant on the sensitivity of method were investigated. The data obtained from the experiments were<br />processed by the partial least squares (PLS), orthogonal signal correction-partial least squares (OSC-PLS)<br />and principle component-back propagation artificial neural network (PC-BPANN). A set of synthetic<br />mixtures of nickel, cobalt and copper was evaluated and the results obtained by each chemometric<br />approaches were compared with different testing methods. The OSC-PLS method was selected because<br />afforded better results than the others. The method was satisfactorily applied for determination of nickel,<br />cobalt and copper in alloy samples. The accuracy was determined using comparing the results to the<br />reference values and also independent analysis by flame atomic absorption spectrometry.