Employment of t-HPSAM in a Nonlinear Spectrophotometric System for Simultaneous Determination of Copper and Zinc

Abstract

A procedure for the selection of wavelength pairs as part of the ternary H-point standard addition method (t-HPSAM) is presented. The t-HPSAM is employed for simultaneous determination of Cu(II) and Zn(II) using murexide as chromogenic reagent. The procedure is based on principal component analysis (PCA), and its advantage is the ability to isolate the analyte signal, even in the presence of apparent nonlinearity. In the present system, non-quantitative complex formation of one of the metal ions with ligand was the reason for nonlinear appearance. In our nonlinear system, selection of the most appropriate pair of variables became possible by means of proper rotation of score and loading plots from PCA. The reliability of the proposed procedure was evaluated using model data. The total relative standard error (RSE) for applying t-HPSAM (coupled with the proposed selection method) to 15 samples in the ranges of 0.00–40.00 µM Cu(II) and 0.00–16.00 µM Zn was 2.56% for Cu and 6.54% for Zn.