Extractive separation and spectrophotometric determination of zinc(II) with thiodibenzoylmethane

Abstract

Thiodibenzoylmethane (3-mercapto-1, 3-diphenylprop-2-en-1-one abbreviated as SDBM) was used for the extraction and spectrophotometric determination of zinc at theμg level. Zinc was quantitatively extracted at pH 8.5 as a yellow colored complex with 5.0 × 10−4M SDBM in benzene. After washing out the excess of the reagent with 2 × 25 ml of 0.05M sodium hydroxide, the complex was measured spectrophotometrically at 410 nm, against the reagent blank, Beer's law was obeyed in the concentration range of 0.15–2.1μg Zn per ml. The molar absorptivity was 3.269 × 104 and the sensitivity was 0.002μg per cm2 per ml. The method is sensitive as well as selective; it is possible to accomplish extraction and photometric determination of zinc in the presence of 1∶3000 of many ions. Ion forming colored complexes, such as copper, cobalt, nickel, palladium, mercury and lead interfere seriously. However, their interference can be eliminated by selective extraction. The overall process of extraction and determination takes 30 minutes. The analysis of zinc in gun metal was also carried out.