Abstract
In the presence of large amount of 1, 10-phenanthroline (phen), the ion-pair of manganese (II) -phen complex with tetraiodofluorescein (TIF) is quantitatively extracted into ethyl acetate from ammonium buffer solution, while the ion-pairs of other metal (II) -phen complexes are not quantitatively extracted at the same condition. This extraction method was applied to the spectrophotometric determination of manganese. The recommended procedure is as follows: to a solution containing up to 1 × 10-7 moles of manganese (II) in a separatory funnel, 1ml of 0.1M phen solution, 1ml of 1 × 10-3M TIF solution and 2ml of ammonium buffer solution (pH 9.5) are added, and the solution is diluted to 10ml with water. After 5min, the solution is shaken with 10ml of ethyl acetate for 7min. After centrifuge, the absorbance of organic phase is measured at 544nm against the reagent blank. Beer's low is held up to 1 × 10-7 d moles of manganese in the 10ml ethyl acetate phase. The extracted complex has a composition of [Mn (II) - (phen)2] (TIF), and its molar absorptivity at 544nm is 1.05 × 105dm3 mol-1cm-1.
