Determination of copper in high purity chromium Chemical analysis of chromium VIII

• Published in: BUNSEKI KAGAKU Vol. 11; no. 1; pp. 108 - 113
• Main Authors: YANAGIHARA, Tadashi, MATANO, Nobuhisa, KAWASE, Akira
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Society for Analytical Chemistry 1962
• ISSN: 0525-1931
• DOI: 10.2116/bunsekikagaku.11.108

A method is described for the determination of trace amounts of copper in high purity chromium. The chromium was dissolved in hydrochloric acid, the pH was adjusted to 3 with sodium acetate and the copper was extracted with zinc diethyldithiocarbamate carbon tetrachloride solution. Copper in the organic layer was taken up in an ammoniacal potassium cyanide solution, and from the difference of absorbance of the organic layer before and after the cyanide treatment the amount of copper was calculated. Iron, nickel, cobalt, silver, mercury, etc. were also extracted in the carbamate extraction at pH3 (Table IV and IX), while the former three was masked with EDTA. Bismuth, even in a microamount, interfered. However, the separation of bismuth from copper was successfully done by treating the carbamate extract with the aqueous ammoniacal cyanide solution, where copper with nickel and a portion of iron was extracted into aqueous phase, while bismuth with cobalt remained undecomposed in the organic layer (Table VI). By combination of these two means, all interferences were practically removed. High purity chromium was analyzed by proposed method and 5.7ppm of copper was successfully determined.