SEPARATION OF TRACE AMOUNTS OF HIGH-VALEN CE 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 an d Hi in Ni were studied. After the sample was dissolved with nitric ac id, Ti, Zr, Mo, Sn and Hf were separated from Ni by extracting into be nzene 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 m ol . 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.