Spectrophotometric determination of osmium with 2-mercaptobenzothiazole

Abstract

A new spectrophotometric method for osmium is described which is based on the extraction of the blue precipitate formed by the reaction with 2-Mercaptobenzothiazole at pH ~ 4, and measurement of absorbance at 590–600 mμ. The color system obeys Beer's law from 2 to 10 μg/ml of osmium, the optimum range being from 5 to 8 μg/ml. The sensitivity of the color reaction and the molor absorptivity of the cationic diligand complex are 0.019 μg/cm 2 and 1 × 10 4, respectively. Small amounts of other platinum metals are permissible. Most of the common base metals are masked by EDTA (disodium salt).