Determination of ruthenium and osmium in each other's presence in chloride solutions by direct and third-order derivative spectrophotometry

Ruthenium and osmium (up to 20 mu g Ru(Os) ml(-1)) can be determined in chloride solutions directly after absorption of RuO4 and OsO4 in hydrochloric acid. In 9 M HCl, RuO4 and OsO4 are quantitatively converted into RuCl62- (lambda(max) = 480.0 nm, epsilon = 4.8 x 10(3) 1 mol(-1) cm(-1)) and OsCl62- (lambda(max) = 334.8 nm. epsilon = 8.4 x 10(3) 1 mol(-1) cm(-1)) respectively. Osmium does not interfere with the determination of ruthenium in thr form of the RuCl62- complex by 6 direct spectrophotometry. The absorbance of the obtained solution at lambda(max) = 480.0 nm corresponds only to the concentration of ruthenium. A derivative spectrophotometric method using numerical calculation of absorption spectra of the RuCl62- and OsCl62- complexes has: been developed for the determination of osmium in a mixture with ruthenium. The interfering effect of ruthenium on the determination of osmium can be eliminated by measuring the value of a third-order derivative spectrum of the OsCl62- complex at 350.0 nm (''zero-crossing point'' of ruthenium). Simple and rapid determination of ruthenium and osmium in a calibration standard solution of the noble metals (Ru, Rh, Pd, Os, Ir, Pt and Au) for plasma spectroscopy using the proposed methods has been achieved.