Photometric determination of small amounts of copper in bismuth metal with diethyldithion-carbamic acid

Abstract

Photometric determination of copper in bismuth with diethyldithiocarbamic acid has been presented. Copper and bismuth are extracted into organic solvent as carbamate complexes and bismuth chelate is easily backextracted into 2N sodium hydroxide solution, while copper chelate is not.One gram of bismuth metal was dissolved in nitric acid (1+1). The pH was adjusted to 89 with ammonis after adding 10 mlof 50% citric acid solution. It was transferred into a separatory funnel, and 1mlof 0.1% sodiumdiethyldithiocarbamate solution was added. The solution was shaken vigorously with 10ml of benzene for 3 min and the aqueous layer was discarded. Twenty ml of 2N sodium hydroxide solution was added into separatory funnel and the mixture was determined from the absorbance of the benzene layer at 435 nm.One hundred μg of each Ni, Co, Te and Pd in 1g of bismuth is not extracted as carbamate. However, in case of the presence of 0.1g of bismuth, a part of Ni, Co and Pd are extracted, and it was necessary to add EDTA for masking the reaction between these ions and carbamic acid. The limit of determination was 1μg.