Determination of cobalt in samples containing cobalt and tungsten carbide by electrothermal atomic absorption spectrometry
Firriolo, J.M.; Kutzman, R.S.
American Industrial Hygiene Association Journal 46(9): 476-480
ISSN/ISBN: 0002-8894 DOI: 10.1080/15298668591395201
A method has been developed to determine the amount of cobalt (Co) in atmospheric dust samples which include free and sintered Co. Cobalt and tungsten carbide (WC) mixtures ranging from 0-100% Co were prepared for atomic absorption analysis by dissolving the Co in aqua regia. Using this method, the amount of Co in the samples assayed ranged from 90.9-100.1% of that gravimetrically added to the mixtures. The results of this aqua regia dissolution procedure for Co were compared to a hydrofluoric acid method which solubilized both the Co and the WC. Application of the aqua regia dissolution method to samples of sintered WC and Co dust resulted in complete recovery of the Co from these materials. These results were supported by X-ray analysis of the samples before and after dissolution of the Co with aqua regia. The described procedure is advantageous because it avoids the use of highly-caustic hydrofluoric acid and the results are quickly available.