Determination of Ruthenium and Osmium with Tin(II) Chloride by Second-Order Derivative Spectrophotometry

Abstract

Ruthenium and osmium can be determined in the same solution by second-order derivative spectrophotometry after a conversion into complexes with tin(II) chloride. In a mixed solution containing 5M (1M=1mol dm^-3) HCl and 0.05M SnCl₂ ruthenium is quantitatively converted, from various oxidation states and various forms, into the complex RuCl₂(SnCl₃)₂^2- after heating for 45min. The value of the second-derivative for the anionic complex with SnCl_3- ligands at 22250cm^-1 (zero-crossing point of osmium) is a measure of ruthenium concentration. Osmium can be determined after heating the solution containing 2M HCl and 0.4M SnCl₂ for 1.5h. At 25900cm^-1 the value of second-derivative is dependent only on osmium concentration (zero-crossing point of ruthenium). Ruthenium, in the concentration range 2-35μg/ml (in the presence up to 450μgOs/ml), and osmium, in the concentration range 7.5-90μg/ml (in the presence up to 45μgRu/ml), can be determined with good precision and accuracy, without separation.