Photcmetric determination of bismuth, copper and tellurium with diethyldithiocarbamic acid

KUROHA Toshiaki, SHIBUYA Seiji

doi:10.2116/bunsekikagaku.21.1197

Successive photometric determination of Bi, Cu and Te has been presented. These colored diethyldithiocarbamate complexes are extracted into organic solvent from the alkaline solution containing EDTA. while other colored metal chelates such as Co, Ni, Fe and Mn are not extracted. Bismuth is easily extracted into over 1 N sodium hydroxide solution from the solution containing its diethyldithiocarbamate, while Cu and Te are not extracted. Bismuth, Cu and Te are extracted into dilute nitric acid from the solution containing these diethyldithiocarbamates. Copper has a greater chelate formation constant with the carbamate than Te and Cd, and gives selectively a substitution reaction with Cd in the complex in the solvent, while Te does not. The recommended procedure is as follows;<BR>The pH of the sample solution containing Bi, Cu and Te was adjusted to 8.08.2 with ammonia after adding 2 ml of 50% citric acid solution and 0.5 ml of 1M EDTA solution. It was transferred into a brown-glass separatory funnel, and 1 ml of 1% sodium-diethyldithiocarbamate solution was added. The solution was shaken vigorously with 10 ml of benzene for 5 min and the aqueous layer was discarded. Fifteen ml of 1N sodium hydroxide solution was added into the separatory funnel and the mixture was shaken for 10 sec. Aqueous layer (A) was transferred into beaker and benzene layer (B) was stored for the determination of Cu and Te. The pH of the aqueous layer (A) was adjusted to 89 with HCl (1+3) after adding 1 ml of 50% citric acid solution. The solution was transferred into a separatory funnel and shaken vigorously with 10 ml Cd-DDC-CHCl₃ solution for 5 min. The amount of Bi was determined from the absorbance of the chloroform layer at 370 nm. Fifteen ml of HNO₃(1 +6) was added into the separatory funnel containing the benzene layer (B) and the mixture was shaken for 1 min. and repeated once more. The pH of all layers of the nitric acids was adjusted to 8.08.2 with ammonia after adding 1 ml of 50% citric acid solution. The solution was transferred into a brown-glass separatory funnel and shaken vigorously with 10 ml of Cd-DDC-CHCl₃ solution for 3 min. The amount of Cu was determined from the absorbance of the chloroform layer at 435 nm. One ml of 0.2% sodium-diethyldithiocarbamate solution was added into the separatory funnel which contained the aqueous solution after the determination of the Cu. The solution was shaken vigorously with 5 ml of chloroform for 1 min. The amount of Te was determined from the absorbance of the chloroform layer at 425 nm.

Photcmetric determination of bismuth, copper and tellurium with diethyldithiocarbamic acid

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