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'Mass Spectrometry' in keywords Facet   Publication Year 1980  [X]
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1Author    Eberhard Hohaus, Wolfgang Riepe, Klaus Wessendorf, LaRequires cookie*
 Title    Massenspektrometrische Untersuchungen an Borchelaten, V [1] Fragmentierung borhaltiger aromatischer Azoverbindungen Mass Spectrometric Investigation of Boron Chelates, V [1] Fragmentation of Aromatic Azo Compounds Containing Boron M+ M+-R M+-RH A M+-C6H5N2 C6H5N2+ C6H5 +  
 Abstract    Differing fragmentation of boron chelates of aromatic azo compounds confirms the structural formulae la-7c, presented in [2]. More significant differences are caused by the substituent of the boron R (F instead of C6H5). Although certain rules can be deduced by the substitution of F for CeHs with regard to the change in intensity of the ions M+, M+-R (and others), in some cases the stable aromatic azo system causes a significant change in the fragmentation as compared with that of azomethine chelates. The chelates 7 eliminate "RH" and show no molecular ion. Apparently a second chelate ring is closed before further fragmentation can start. Fragmentation of 7 a and b is analogous to 5. Einführung Die Massenspektrometrie nimmt bei der analyti-schen Überprüfung und der Konstitutionsaufklä-rung von Borchelaten eine besondere Stellung ein, weil umfangreiches Material mit verschiedensten Komplexbildnern vorliegt. Deshalb werden die Er-gebnisse der Azochelate [2] mit denen der früher dargestellten verglichen. Die Numerierung der Che-late erfolgt nach dem Formelschema in [2]. Vergleich der Fragmentierungen Chelate 1 und 2: Das Massenspektrum von la zeigt nur eine geringe relative Intensität für das Tab. I. Nr. 
  Reference    Z. Naturforsch. 35b, 316—318 (1980); eingegangen am 8. Oktober 1979 
  Published    1980 
  Keywords    Mass Spectrometry, Boron Azo Chelates, Fragmentation 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0316.pdf 
 Identifier    ZNB-1980-35b-0316 
 Volume    35 
2Author    Helmut Schwarz, Chrysostomos Wesdemiotis, Thomas Weiske, Klaus-Peter Zeller, Roland MüllerRequires cookie*
 Title    H. Schwarz et al. * Methyl-Eliminierung aus dem metastabilen Homoadamantan-Radikalkation 219 Methyl Loss from Metastable Homoadamantane Cation Radical  
 Abstract    It is demonstrated that methyl loss from ionized homoadamantane (1) yields exclusively the 1-adamantyl cation (4); there is no experimental evidence for the formation of the secondary adamantyl cation (5). From both model calculations and the investigation of [4-13 C]-homoadamantane (la) and l(13 C-methyl)adamantane (2a) it is concluded, that 24% of the metastable homoadamantane cation radicals dissociate after one isomerization (1 2); the remaining 76% are able to undergo at least a second (degenerate) isomerization cycle (2->l->2) prior to methyl loss. 78% of metastable 1-methyl-adamantane cation radical, obtained upon direct ionization of the corresponding neutral hydrocarbon, dissociate directly, whereas the loss of methyl from the remaining 22% is preceded by an isomerization 2 ->1 ->2. 
  Reference    Z. Naturforsch. 35b, 207—211 (1980); eingegangen am 23. Oktober 1979 
  Published    1980 
  Keywords    Ion Structures, Carbocation Rearrangements, Hydrocarbon Chemistry, Mass Spectrometry, Collisional Activation 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0207.pdf 
 Identifier    ZNB-1980-35b-0207 
 Volume    35 
3Author    R. Ziskoven, C. Achenbach, U. Bahr, H.-R SchultenRequires cookie*
 Title    Quantitative Investigations on the Diaplacental Transfer of Thallium by Field Desorption Mass Spectrometry  
 Abstract    The placental transfer of thallium cations in pregnant mice was investigated by determining the thallium concentrations in fetal and maternal tissue 0.5 to 24 h after application of thallium. The maternal dose o f thallium was 8 mg/kg body weight throughout. Uterus and fetus were found not to differ from other organs like heart and liver in time course and magnitude of thallium uptake with an initial surge during the first few hours of exposure to thallium and a rapid decrease to steady 12 and 24 h values somewhat lower than those found in the kidney. Diaplacental transfer is therefore assumed comparatively rapid and a specific placental barrier for thallium does not seem to exist. For the determination of thallium concentrations Field Desorption Mass Spectrometry was utilized as a reliable, fast, and sensitive method for the analysis o f metal cations in biological material. This method does not require extensive pretreatment of the tissue and total sample amounts in the range of milligrams and less are sufficient for quantitative analysis. 
  Reference    Z. Naturforsch. 35c, 902 (1980); received August 8 1980 
  Published    1980 
  Keywords    Thallium, Placental Transfer, Ultratrace Determination, Mass Spectrometry, Field Desorption 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0902.pdf 
 Identifier    ZNC-1980-35c-0902 
 Volume    35