Spectrophotometric Determination of Osmium and Ruthenium with N-Benzoyi-Ń-Methylphenyl Selenourea

Chemical Laboratory, Presidency College, Caleutta-700 073 (India) Manuscript received 20 May 1979, accepted 30 November 1979 N-benzoyl-Ń-methylphenyl selenourea is recommended as a chelating agent for the spectrophotometric determination of osmium(VI) and ruthenium(III). It forms a wine red complex with osmium(VI) which can be quantitatively extracted with chloroform at pH 4.20-5.50. The reagent forms a reddish-brown complex with ruthenium(III). Quantitative extraction of ruthenium is obtained from a solution at 0.8M-3.0M hydro­chloric acid. The chloroform extracts of both osmium and ruthenium complexes show maximum absorption at 460 nm and Beer's law is obeyed over the concentration ranging from 2 83 μg to 28.30 μg Os(VI)/ml and 0.65 to 9.81 μg Ru(III)/ml. The reagent forms 2: 1 and 3 : 1 complexes with osmium and ruthenium respectively. The advantage of the use of N-benzoyl-N'-methylphenyl selenourea as a spectrophotometric reagent for both osmium and ruthenium lies in the fact that these metal ions can be determined in presence of all base metals and large excess of all other platinum metals. Simultaneous determination of osmium and ruthenium is possible with the chelating agent