Extraction-spectrophotometric determination of indium using 4-(2-pyridylazo)resorcinol

Abstract

A simple extraction-spectrophotometric procedure for the determination of microamounts of indium is reported. Indium is quantitatively extracted from the aqueous phase at pH 5.0–5.5 into chloroform with N-p-chlorophenyl-2-furohydroxamic acid and determined spectrophotometrically using 4-(2-pyridylazo)resorcinol. The red mixed complex of indium absorbs at 520 nm with a molar absorptivity of 3.0 × 10⁴ l mol^–1 cm^–1. The system obeys Beer's law from 0.18 to 3.70 p.p.m. of indium. The effects of pH, reagent and PAR concentrations, shaking time, diverse ions and the stoicheiometry are discussed. The results obtained using the proposed method are compared with those obtained by atomic absorption spectrometry, which may be applied to the extracted indium. The merits and demerits of several other spectrophotometric methods for indium are also discussed.