Yasuharu Nishikawa

Simultaneous determinations of metal 5-sulfo-8-quinolinolates by differences in their fluorescence lifetimes

Abstract Fluorescence lifetimes of aluminium, gallium, indium, magnesium, zinc, and cadmium 5-sulfo-8-quinolinolates are reported. A method for the simultaneous determination of two components based on the difference in their fluorescence lifetimes is given. The method is applied to determinations of aluminium in magnesium alloy and of magnesium in aluminium alloy. The procedure is simple and rapid, and gives accurate results.

Chemical forms of chromium in natural water

The interaction of chromium (III) with humic substances obtained from pond sediment was experimentally studied using electrophoresis combined with ultrafiltration. The results show that within the neutral pH range chromium (III) in the presence of humic substances and some organic acids forms uncharged and/or negatively charged organic complexes of various molecular weights. A part of the chromium(III)-humic or -fulvic acid complexes having a negative charge was of lower molecular weight. Chromium (III) spiked in fresh water exists as various soluble anionic and/or uncharged species, and the molecular weights of these anionic complexes correspond to those of chromium(III)-humic and -fulvic complexes. These complexes may remain as stable dissolved forms for 10 days. The significance of the occurrence of chromium(III)-organic complexes in natural water in the geochemical cycle of chromium in the hydrosphere is discussed.

Simultaneous fluorimetric determination of 8-quinolinol and 5,7-dihalo-8-quinolinols by differences in their fluorescence lifetimes

Abstract A method is described for the simultaneous determination of 8-quinolinol and 5,7-dihalo- 8-quinolinols, without preliminary separation, based on the difference in their fluorescence lifetimes. The method is applied to mixtures of 8-quinolinol (τ, 22.8 ns)and 5,7-dibromo-8-quinolinol (τ, 6.0 ns) or 5,7-dichloro-8-quinolinol (τ, 9.7 ns). The procedure is simple and rapid and is suitable for 10-5—10-7 mol l-1 concentrations.

Analysis of the fluorescence spectra on Kimuraite.

佐賀県東松浦郡肥前町産の木村石[CaY2(CO3)4・6H2O]は紫外線照射により赤紅色の蛍光を発する.この発光は鉱物中に含まれるEu(III), Tb(III), Gd(III)及びDy(III)イオンの輝線スペクトルに起因することを明らかにした.これら発光性希土類金属(III)化合物の蛍光スペクトルの帰属とその分光特性を詳細に検討した結果,木村石の蛍光スペク.トルはそれぞれEu(III):Ex.395(7F6→5Le)/Em.615nm(5D0→7F2);Tb(III):Ex.380(7F6→5D3)/Em.545nm(5D4→7F5);Gd(III):Ex.275(8S7/2→6D3/2)/Em.312nm(6P7/2→8S7/2);Dy(III):Ex.352/Em.575 nm(4F9/2→6H13/2);の4f電子の許容遷移に基づく発光であることを明らかにした.

SOLVENT EXTRACTION SEPARATION OF SCANDIUM FROM YTTRIUM AND RARE EARTH ELEMENTS

The solvent extraction separation of Sc from Y and rare earths with acetylacetone or dibenzoylmethane was studied. In order to find out a convenient method, the above methods were compared with conventional thiocyanate method and TTA method. The extractability was determined radiometrically, using radioactive isotopes, Sc/sup 46/, Y/sup 91/, Eu/sup 152 and Lu/sup 177/ as tracers. The last two elements were selected as the representatives of rare earths. The extraction recoveries of scandium obtained under each optimum condition are given. From the results it was revealed that both the acetylacetone- and dibenzoylmethane-benzene (or chloroform) systems are as usefui as the TTA-benzene system. Among them the extraction with acetylacetone or TTA is convenient as far as the separation of Sc from Y and rare earths is concerned. However TTA is better than acetylacetone, because the extraction can be performed at lower pH region. (P.C.H.)