Extractive separation and spectrophotometric determination of microamounts of tin(IV)

Abstract

A simple solvent extraction and spectrophotometric method for the determination of microamounts of tin is described. Tin is selectively separated from associated elements by extracting it with N-p-chlorophenyl-2-furohydroxamic acid from an aqueous phase containing 5 M perchloric acid and determined by spectrophotometry using 4-(2-pyridylazo)resorcinol (PAR). The molar absorptivity of the ternary complex is 5.18 × 10⁴ l mol^–1 cm^–1 at 480 nm. The coloured system obeys Beer's law in the range 0.1–3.2 p.p.m. of Sn(IV). The spectral characteristics of the tin complexes with six chloro-substituted hydroxamic acids and PAR are listed and the optimum working conditions of the method are discussed. The method has been applied to the determination of tin in standard brass and bronze samples and a comparison with several other spectrophotometric methods for the determination of tin has also been made.