| 18963230 |
Gomis DB, Jimeno SA, Sanz-Medel A: Extraction-spectrophotometric determination of niobium with dibenzo-18-crown-6 and thiocyanate. Talanta. 1982 Sep;29(9):761-5.
A method is described for the direct spectrophotometric determination of micro-amounts of niobium by extraction into a benzene solution of dibenzo-18-crown-6 (L) from 3M hydrochloric acid containing potassium thiocyanate. The molar absorptivity of the extracted complex is 3.85 +/- 0.03 x 10 (4) 1.mole (-1).cm (-1) (relative standard deviation 0.8%). Co-ordinatively unsaturated complexes of the type [NbO (SCN)(3)](2) L and NbO (SCN)(3) L are extracted, along with ion-pairs, especially when small amounts of L are used for extraction. The ion-pair complex [NbOCl (2)(SCN)(3)][(LK)(2)] seems to be the main species formed in the organic phase. |
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