Separation of antimony(III) with iodide and dithizone by sorption on polyurethane foam from sulphuric acid medium for its spectrophotometric determination in glasses

Abstract

A method for quantitative separation of antimony(III) by sorption on polyether based polyurethane foam and its spectrophotometric determination has been described. The method involves formation of a pink—red complex of antimony(III) with iodide (0.045 M) and dithizone (2.3 × 10 −5 M) in 0.25–0.75 M H 2SO 4 medium, sorption of the complex on polyurethane foam (within 45 min) at room temperature followed by its elution with acidified acetone (acetone containing 0.008% H 2SO 4) and spectrophotometric measurement at 507.2 nm (ϵ = 2.56 × 10 4 l mol cm). The method obeys Beer's law from 0.1 to 6.0 μg antimony(III). Tolerance limits of other ions are Co (100 μg), Ni (100 μg), Fe (10 μg), Cu (0.5 μg), Sn (20 μg), Zn (100 μg), As (100 μg), Mn (200 μg), Pb (50 μg), Ti (100 μg), V (50 μg), etc. Interference by iron and copper have been eliminated by treating with KOH prior to the extraction of antimony. The method has been standardized with glass samples spiked with known amounts of antimony and applied to the determination of antimony in various glasses.