Separation of trace amounts of high-valence elements in nickel with extraction and back-extraction using N-benzoyl-N-phenylhydroxylamine

The separation and determination of trace amounts of Ti, Zr, Mo, Sn and Hi in Ni were studied. After the sample was dissolved with nitric acid, Ti, Zr, Mo, Sn and Hf were separated from Ni by extracting into benzene with N-benzoyl-N-phenylhydroxylamine (BPA) and subsequently back-extracted into nitric acid for the determination by ICP-AES or ICP-MS. The recoveries of Ti, Zr, Mo, Sn and Hf were satisfactory throughout the extraction with 4.0 x 10(-2) mol dm(-3) BPA in benzene from 1.0 mol . dm(-3) nitric acid-0.1 mol . dm(-3) trichloroaceticacid solution and the back-extraction with 60% nitric acid. The separation factors (S-M=D-M/D-Ni, D=distribution ratios) of Ti, Zr, Mo, Sn and Hf from Ni were 9.9 x 10(3) for Ti, 3.2 x 10(4) for Zr, 3.2 x 10(4) for Mo, 1.3 x 10(3) for Sn and 4.0 x 10(4) for Hf. The recoveries of Ti, Zr, Mo, Sn and Hf decreased somewhat with increasing the added amount of Ni. The detection limits by ICP-MS were found to be 0.031 mu g . g(-1) for Ti, 0.046 mu g . g(-1) for Zr, 0.014 mu g . g(-1) for Mo, 0.7 mu g . g(-1) for Sn and 0.006 mu g . g(-1) for Hf using 0.5 g of Ni sample. The proposed method was applied to analysis of the real sample.