Application of Thionine Dye for Highly Sensitive and Selective Catalytic ‎Kinetic Determination of Osmium

A new, highly sensitive and selective ‎catalytic kinetic method (CKM) for ‎determination of osmium (VIII) has ‎been established based on its ‎catalytic effect on the oxidation of ‎thionine dye by hydrogen peroxide ‎in alkaline medium. The reaction ‎has been followed ‎spectrophotometrically by ‎measuring the decrease in the ‎absorbance band of thionine at ‎‎600 nm. Under the optimum ‎conditions, the proposed method ‎allows determination of osmium ‎concentrations in the range of 0.1 - ‎‎220 ng ml-1 with a detection limit ‎of 0.015 ng ml-1. The relative ‎standard deviations for 11 ‎replicate determinations of 0.20, ‎‎2.0 and 20 ng ml-1 osmium (VIII) ‎were 3.3, 1.0 and 0.69%, ‎respectively. This method is free ‎from of most interferences, highly ‎selective, sensitive and very stable