Solid-liquid separation after liquid-liquid extraction: spectrophotometric determination of copper by extraction of its 1-phenyl-4,4,6-trimethyl-(1H,4H)-pyrimidine-2-thiol into molten naphthalene

Abstract

A selective spectrophotometric method has been developed for the determination of copper after extraction of its 1-phenyl-4,4,6-trimethyl-(1H,4H)-pyrimidine-2-thiol (PTPT) complex into molten naphthalene. The optimum pH range for the extraction is 7.4–11.7. The solid naphthalene containing the copper - PTPT complex is separated by filtration and dissolved in chloroform. The absorbance is measured at 400 nm against a reagent blank. Beer's law is obeyed in the concentration range 5.0–60.7 µg of copper in 10 ml of chloroform solution. The molar absorptivity and sensitivity are 1.23 × 10⁴ 1 mol^–1 cm^–1 and 0.008 11 µg cm^–2, respectively. The interference of various ions has been studied in detail. Conditions have been established for the determination of copper in goat liver, human hair and certain alloys.