抄録
Manganese (II) reacted with thiothenoyltrifluoroacetone (STTA) in the presence of 1, 10-phenanthroline (phen) to form a complex, Mn(STTA)2(phen). The complex extracted into xylene had an absorption maximum around 375 nm and the absorbance was stable at least for 24 h. The analytical procedure was as follows: To a sample solution containing less than 15μg of manganese (II), were added each 5 ml of 20 w/v % ammonium acetate solution and 3.0 × 10-4M phen solution. The pH of the mixture was adjusted to 7.3 ±0.3 with ammonia water and the solution was diluted to 50 ml with water. The manganese (II) in the solution was extracted with 10 ml of 3.15 × 10-4 M STTA solution in xylene by shaking for 5 min. The aqueous phase was removed and the organic phase was washed with 10 ml of borax-NaOH buffer solution (pH 11.5) by shaking for 1 min. Then the absorbance of the organic phase was measured at 375 nm against the reagent blank. In the determination of 10 μg of manganese (II), 1.0 μg of zinc (II), cadmium (II), copper (II), and cobalt (II) interfered. However, these (interfering) metal ions were removed by the prelim inary extraction at pH 7.3±0.3 with STTA solution in xylene in the absence of phen, because manganese (II) was not extracted under these conditions. The calibration curve was linear up to 15μg of manganese (II) in 10 ml of the organic phase. The coefficient of variation on the absorbance for 10 μg of manganese (II) was 0.8 %. The molar absorptivity was 3.58× 104 l mol-1 cm-1. The proposed method could be applied to the determination of manganese in aluminum and aluminum alloys with satisfactory results.
