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1Author    KlausG. Heumann, Paul Roßmann, Anni Schwarz, Alfred WindfelderRequires cookie*
 Title    Abhängigkeit der Chlor-Isotopenseparation vom Vernetzungsgrad eines stark basischen Anionenaustauschers Dependence of Chlorine Isotope Separation on the Degree of Cross Linkage of a Strongly Basic Anion Exchange Resin  
 Abstract    Using ion exchange chromatography, the dependence of the chlorine isotope separation on the degree of cross linkage of a strongly basic anion exchange resin was investigated. With increasing degree of cross linkage the elementary separation effect for the two stable isotopes 35 C1 and 37 C1 increases. In all experiments 35 C1~ is enriched in the resin phase, whereas 37 C1~ is enriched in the solution, using 0.1 M NaNC>3 as an eluant. Within the degree of cross linkage of 2 to 10 per cent investigated, there is a linear correlation of the elementary separation effect of the chlorine isotopes with the selectivity coefficient between the ions NO3"" and Cl -. The results show that the electrolyte behavior of anionic isotope exchange reactions is comparable with that of cations. The 35 C1/ 37 C1 isotope ratio is determined using thermal ionization mass spectrometry. Untersuchungen von Isotopieeffekten bei hetero-genen Ionenaustauschreaktionen sind bereits bei einigen Kationen durchgeführt w T orden, wie z.B. 
  Reference    Z. Naturforsch. 34b, 406—411 (1979); eingegangen am 4. Dezember 1978 
  Published    1979 
  Keywords    Isotope Separation, Chlorine, Ion Exchange Chromatography, Mass Spectrometry 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0406.pdf 
 Identifier    ZNB-1979-34b-0406 
 Volume    34 
2Author    KlausG. Heumann, Helmut KlöppelRequires cookie*
 Title    Abhängigkeit der Calcium-Isotopenseparation bei der Ionenaustauschchromatographie von der HN03-Elutionsmittelkonzentration Calcium Isotope Separation by Ion Exchange Chromatography in Dependence on the HNO3 Eluant Concentration  
 Abstract    Using a strongly acidic cation exchanger resin, the dependence of the calcium isotope separation on the HNO3 eluant concentration is investi-gated on column experiments. The elementary separation effect of the isotope ratios 44 Ca/ 40 Ca and 48 Ca/ 40 Ca is determined. Up to HN03 concentrations of about 1.5 M the lighter calcium isotopes are enriched in the resin phase, whereas, using more concentrated HN03 solutions, the heavier isotopes are enriched in the ion ex-changer. A comparison of these results with those using hydrochloric acid and perchloric acid show, that there is a strong dependence of the isotope separation on the concentration and the counter ion of the eluant solution. 
  Reference    Z. Naturforsch. 34b, 1044—1045 (1979); eingegangen am 22. Januar 1979 
  Published    1979 
  Keywords    Isotope Separation, Calcium, Ion Exchange Chromatography 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1044_n.pdf 
 Identifier    ZNB-1979-34b-1044_n 
 Volume    34 
3Author    KlausG. Heumann, Hans-Peter SchieferRequires cookie*
 Title    Calciumisotopenseparation mit Kryptanden als Komplexbildner Separation of Calcium Isotopes with Cryptand Complexes  
 Abstract    The calcium isotope separation in the liquid-liquid extraction system H2O/CHCI3 is investigated using [2.2.1] and [2.2.2] cryptands for complex formation as well as without complexing agent. An extraction procedure is used which allows the transfer of larger amounts of calcium into the CHCI3 phase although the high distribution coefficient favours calcium in the H2O phase. Without complexing agent in the extraction system, enrichment of the lighter calcium isotopes is already evident in the CHCI3 phase which is just the same as when using [2.2.1] cryptand. In the case of [2.2.2] cryptand as a com-plexing agent, the isotope separation is higher. The separation factor is calculated to be a = 1 + e = 1.011 for 40 Ca/ 48 Ca without complexing agent or with [2.2.1] cryptand and a = 1.015 in the system with [2.2.2] cryptand. For 40 Ca/ 44 Ca the e-value is smaller by nearly a factor of two. These separation factors are the highest which are determined in chemical systems for calcium isotopes. 
  Reference    Z. Naturforsch. 36b, 566—570 (1981); eingegangen am 17. Dezember 1980 
  Published    1981 
  Keywords    Isotope Separation, Calcium, Cryptand, Liquid-Liquid Extraction 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-0566.pdf 
 Identifier    ZNB-1981-36b-0566 
 Volume    36 
4Author    KlausG. Heumann, H. Klöppel, G. SiglRequires cookie*
 Title    Inversion der Calcium-Isotopenseparation an einem Ionenaustauscher durch Ver- änderung der LiCl-Elektrolytkonzentration Inversion of the Calcium Isotope Separation at an Ion Exchanger Resin by Variation of the LiCl Electrolyte Concentration  
 Abstract    The calcium isotope separation at a strongly acidic exchanger resin as a function of the concentration of a LiCl solution is investigated in column experiments. Whereas an enrichment of the heavier calcium isotopes in the solution phase is found with a 3 M LiCl solution, an inverse effect is obtained with 8 M and 12 M LiCl solutions. The separation effect e for the 12 M solution is found to be the highest calcium enrichment in a system without a complexing agent. The results are compared with those for other electrolyte solutions and can be explained by the anion/cation interactions. 
  Reference    Z. Naturforsch. 37b, 786—787 (1982); eingegangen am 1. Februar 1981 
  Published    1982 
  Keywords    Isotope Separation, Calcium, Strongly Acidic Cation Exchanger, Concentration Dependence 
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 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-0786_n.pdf 
 Identifier    ZNB-1982-37b-0786_n 
 Volume    37 
5Author    Morikazu Hosoe, Takao Oi, Tadashi Nagumo, Hidetake KakihanaRequires cookie*
 Title    Rubidium Isotope Separation by Constant Current Electromigration in a Cation-exchange Membrane  
 Abstract    Separation of rubidium isotopes (85 Rb, 87 Rb) by electromigration in a cation exchange mem-brane has successfully been carried out in a band operation manner at 25 °C. The migration velocity has been varied from 2.5 to 12.1 cm/h. There existed a wide non-isotope-fractionated zone between the 85 Rb enriched zone at the front and the 85 Rb depleted zone at the rear of the band. The single stage separation factor was about 1.0009 and was independent of the migration velocity, migration length and operation technique at a given temperature. The steepness of the 85 Rb accumulation curves, increased with increasing migration velocity. 
  Reference    Z. Naturforsch. 42a, 606—610 (1987); received March 5 1987 
  Published    1987 
  Keywords    Isotope separation, isotope effect, electromigration, rubidium isotope, ion-exchange membrane 
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 TEI-XML for    default:Reihe_A/42/ZNA-1987-42a-0606.pdf 
 Identifier    ZNA-1987-42a-0606 
 Volume    42 
6Author    KlausG. Heumann, Klaus Baier, Gerald WibmerRequires cookie*
 Title    Chlor-Isotopenseparation an einem wasserhaltigen Zirkondioxidaustauscher Chlorine Isotope Separation Using an Hydrous Zirconium Dioxide Exchanger  
 Abstract    zirconium dioxide is used in column experiments for separating the halide ions as well as for isotope fractionation of chlorine. The preparation of the zirconium dioxide particles is carried out by homogeneous hydrolysis of a zirconyl chloride solution using hexamethylenetetramine. The separation order of the halides is I -, Br -and Cl -in contrast to the inverse separation order using a strongly basic anion exchange resin. In chlorine isotope separation experiments an enrichment of 35 C1~ is found in the first fractions, whereas the last fractions show a significant enrichment of 37 C1~. This also indicates an inversion of the isotope separation compared with a strongly basic anion exchange resin. A dependence of the isotope fractionation on the concentration of the NaNC>3 solution used as eluant is found. With increasing concentration the isotope fractionation decreases. Using a 0.5 M NaN03 solution the elementary separation effect was calculated e = 6,1 • 10~ 4 . This is one of the highest isotope fractionations known in a chloride isotope exchange system. The results show that the electrolyte behaviour of isotopes is comparable to that of a series of homologous elements. 
  Reference    Z. Naturforsch. 35b, 642—647 (1980); eingegangen am 11. Januar 1980 
  Published    1980 
  Keywords    Isotope Separation, Chlorine, Zirconium Dioxide, Column Experiments, Halide Separation Hydrous 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0642.pdf 
 Identifier    ZNB-1980-35b-0642 
 Volume    35 
7Author    Takao Oi, Hirotsugu Takeuchi, Akiko Sakurai, Yoshifumi Taguchi, Morikazu HosoeRequires cookie*
 Title    Boron Isotope Effect in Liquid Chromatography with Boron-specific Resins as Packing Material  
 Abstract    Boron isotope separation by liquid chromatography using boron specific resins with N-methyl glucamine as the functional group was performed. The single-stage separation factor, S, is generally dependent on the resin in the sequence S (free base form resin) > S (F~ form resin) >5 (CP form resin) ^S (Br ~ form resin) for given experimental conditions. This sequence is the same as that of the pH value expected in the resin phase and reasonably understandable by assuming in addition to the predominant four-coordinate species a three-coordinate boron species in the resin phase whose relative abundance increases with decreasing pH. Supporting evidence for three-coordinate species was obtained by 1: B NMR measurements of boric acid-glycerol and boric acid-l,3-propane-diol solutions. 
  Reference    Z. Naturforsch. 52a, 821—827 (1997); received May 23 1997 
  Published    1997 
  Keywords    Boron isotopes, isotope separation, boron specific resin, liquid chromatography, "BNMR 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0821.pdf 
 Identifier    ZNA-1997-52a-0821 
 Volume    52