Solvent extraction of copper as its ion association complex with ethyl violet and its application to the spectrophotometric determination of copper

Abstract

Several cationic dyes were evaluated as reagents for the extraction and spectrophotometric determination of copper. Of the dyes examined, ethyl violet was the most useful reagent. The method is based on the reduction of copper(II) to copper(I) with ascorbic acid, the formation of dichlorocuprate(I) by the reaction of copper(I) with chloride and its extraction into toluene as an ion associate with ethyl violet. For the determination of copper, the absorbance of a toluene solution at 612 nm was measured against a reagent blank. The calibration graph obeyed Beer's law over the range 0–1.4 × 10^–5M copper (in toluene) and the apparent molar absorptivity was 9.65 × 10⁴ I mol^–1 cm^–1.