Determination of Traces of Osmium Tetroxide by the Fluorescence of the OsO4,-4, 6-Bismethylthio-5-Aminopyrimidine System

Abstract

An indirect method for the determination of OsO₄, in the p.p.m. region is possible by measuring the decrease in fluorescence of the 4,6-bismethylthio-5-aminopyrimidine when OsO₄, is added. At liquid N₂ temperatures 10 p.p.b. OsO₄, can be detected. The OsO₄, to ligand ratio was found to be 2:3. For 1 p.p.m. OsO₄, 10 p.p.m. Ir⁺³, 1 p.p.m. Fe⁺³ and less than 1 p.p.m. Ru⁺³ and Pd⁺² can be tolerated. The fluorescent system is not affected by pH in the 3–12 ranges. It is suggested that the decrease in fluorescence results from a complexation reaction with the first site of reaction being the NH₂. group. With increasing OsO₄, concentration, oxidation appears to occur which produces a black product. This oxidation was not observed at p.p.b. concentrations of Os.