Selective Flotation-Spectrophotometric Determination of Trace Copper(II) in Natural Waters, Human Blood and Drug Samples Using Phenanthraquinone Monophenylthiosemicarbazone

Abstract

Copper(II) forms 1:1 and 1:2 intense red complexes with phenanthraquinone monophenylthiosemicarbazone (PPT) at pH 3-3.5 and ≥6.5, respectively. These complexes exhibit maximal absorbance at 545 and 517 nm, the molar absorptivity being 2.3×10⁴ and 4.8×10⁴ l mol^-1cm^-1, respectively. However, the 1:1 complex was quantitatively floated with oleic acid (HOL) surfactant in the pH range 4.5-5.5, providing a highly selective and sensitive procedure for the spectrophotometric determination of Cu^II. The molar absorptivity of the floated Cu-PPT complex was 1.5×10⁵ l mol^-1cm^-1. Beer’s law was obeyed over the range 3-400 ppb at 545 nm. The analytical parameters affecting the flotation process and hence the determination of copper traces were reported. Also, the structure of the isolated solid complex and the mechanism of flotation were suggested. Moreover, the procedure was successfully applied to the analysis of Cu^II in natural waters, serum blood and some drug samples.