SPECTROPHOTOMETRIC DETERMINATION OF MICROGRAM QUANTITIES OF OSMIUM WITH DIPHENYLCARBAZIDE

A method was developed for the spectrophotometric determination of 30 to 100 mu g of osmium. The osmium as OsO/sub 4/ is extracted with CHCl/sub 3/ and diphenylcarbazide is then added to the organic extract. A blue-violet reaction product is formed, the absorbancy of which is measured at 560 m mu . A suitable reagent concentration is from 3 to 5 ml of 0.2% diphenylcarbazide in a volume of 25 ml and the preferred solvent for the reagent is ethanol. Beer's law is followed over a range of 8 to 130 mu g of osmium with a coefficient of variation of about 4 After a 2-hr color-development period the molar absorbancy index is 31,300. Attempts to achieve reproducible measurements of absorbancy in less than 2 hr were unsuccessful. A study was made of the effects of foreign elements and only Ru(VIII) was found to interfere. (auth