Extraction-spectrophotometric determination of cadmium

Abstract

A simple and sensitive extraction-spectrophotometric method for the determination of cadmium is described. The binary complex formed between cadmium and N-phenylcinnamohydroxamic acid (PCHA) is extracted with chloroform at pH 9.5, and shows maximum absorbance at 380 nm with a molar absorptivity of 3.6 × 10³ l mol^–1 cm^–1. The optimum concentration range for measurements is 1.41–11.25 p.p.m. The sensitivity of the method was increased by the addition of 4-(2-pyridylazo)resorcinol (PAR) after extracting cadmium with PCHA at pH 9.5. The Cd-PCHA-PAR complex is reddish orange and shows maximum absorbance at 510 nm with a molar absorptivity of 4.8 × 10⁴ l mol^–1 cm^–1. It obeys Beer's law over the range 0.23–2.25 p.p.m. Various experimental parameters were studied for establishing the optimum conditions for the determination of cadmium. The method had been applied to the determination of cadmium in standard and environmental samples.