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  • Analytical Chemistry and Spectroscopy  (122)
  • Organic Chemistry  (37)
  • Wiley-Blackwell  (159)
  • International Union of Crystallography
  • 1985-1989  (153)
  • 1970-1974
  • 1940-1944  (6)
  • 1987  (153)
  • 1944  (6)
Sammlung
Verlag/Herausgeber
  • Wiley-Blackwell  (159)
  • International Union of Crystallography
Erscheinungszeitraum
  • 1985-1989  (153)
  • 1970-1974
  • 1940-1944  (6)
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 16 (1987), S. 161-165 
    ISSN: 0049-8246
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Oil was chosen as a new sampl type for total reflection XRF. A thin-film sample procedure is described which requires minimal sample preparation. This involves first bringing the oil into solution with a volatile solvent, then pipetting microliter amounts on to the reflector substrate followed by evaporation of the solvent. The linear dynamic range was found to extend to at least 5000 ppm. Detection limit measurements show that minute sample quantities are necessary for optimal detection limits of nanogram amounts. A maximum sample loading is required for the best detection limits in ppm. Using an Mo or Cu X-ray tube, limits were found to be a few ppm or sub-nanogram amounts. The spectrometer was calibrated by an internal standardization method and the results of determinations on sample solutions were typically within 10% relative accuracy.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 1040-1045 
    ISSN: 0749-1581
    Schlagwort(e): α-retinal ; α-ethyl retinoate ; α-retinol ; α-retinoic acid ; 3,4-dehydroretinal ; 3,4-dehydroretinol ; ethyl 3,4-dehydroretinoate ; 3,4-dehydroretinoic acid ; 2D heteronuclear-correlated spectroscopy ; APT ; empirical chemical shift calculations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 13C NMR assignments have been made for a series of 36 α- and 3,4-dehydroretinoids with different substituents (alcohol, ester, aldehyde and acid) and for their separated E and Z geometrical isomers. The assignments were made by using 2D heteronuclear-correlated NMR experiments. From the chemical shift data of 24 systematically related retinoids, empirical chemical shift changes due to four polar end groups (alcohol, aldehyde, carboxylic acids and esters), three chain configurations (all-E, 9Z and 13Z), and two ring substitutions (2,6,6-trimethyl-cyclohex-2-enyl and 2,6,6-trimethylcyclohexa-1,3-dienyl) were determined. All trends were found to be independent of each other, except for the dependence of the chemical shift change of the 13Z-isomers on the polar end groups. The chemical shift changes were used to predict the chemical shifts of other retinoids based on two different ring structures (2,6,6-trimethylcyclohexenyl and 4-methoxy-2,3,6-trimethylphenyl).
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Crystal structures and electrical properties of radical-cation salts of the chiral organic donor TMET (S,S,S,S,-bis-(dimethylethylenedithio)tetrathiafulvalene) are described. Two structural types, 2:1 with octahedral anions Pf-6, AsF-6, SbF-6, I-3 (incommensurate), and 3:2 with tetrahedral anions BF-4, CIO-4, ReO-4 are observed. Resistivity measurements between 2 and 298 K indicate that the 3:2 types are organic metals, while the other compounds are semiconductors. (TMET)3(CIO4)2 is metallic down to about 120 K at ambient pressure and remains metallic down to 2 K at 8 kbar.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 329 (1987), S. 343-348 
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 3-Substituted 4H-Pyrazolo[5,1-c][1,4]benzoxazines by Intramolecular Nitrile Imine Addition
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 329 (1987), S. 311-320 
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Determination of the Molar Absorptivity (ε) of the Photoisomers of 3β-Hydroxy-cholest-5.7-diene (Provitamin D3)A method is described which allows the determination of the molecular absorptivity (ε) of all components in a four-component system and is applied to the ε-determination of the photoisomers of provitamin D3 (1): prävitamin D3 (2), lumisterol3 (3), and tachysterol3 (4). By means of irradiation with appropriate wavelengths the four-component system is reduced to a two- and a three-component system, respectively, and the unknown molar absorptivities are evaluated numerically or graphically.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 329 (1987), S. 55-61 
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Intramolecular 1,3-Dipolar Cycloadditions of Aryl Azides with Alkynyl SubstituentsReaction of substituted 4-chlorobut-2-ynes 1 with 2-acetaminophenol and 2-aminothiophenol, respectively, leads to the corresponding ethers and thioethers 3 that can be converted into the alkynyl substituted aryl azides 4 by diazotation and reaction with sodium azide. Intramolecular 1,3-dipolar cycloaddition yields 4H-[1,2,3]triazolo [5,1-c] [1,4] benzoxazines and benzothiazines 5. In the same way 1,4-bis(2-acetaminophenoxy)but-2-yne 6 reacts to a 3-(2-azidophenoxy-methyl)-triazolobenzoxazine 9. Its thermal decomposition gives the azomethine 11.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 213-220 
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermospray HPLC/MS analysis of the metabolites of arachidonic acid proved to be sensitive and specific. The compounds included were hydroxy-fatty acids (5-HETE, 12-HETE, and 15-HETE) and prostaglandins PGD2, PGE2, PGF2α, PGA2, PGA1, TXB2, and 6-Keto-PGF1α. Thermospray HPLC/MS analysis allows for simultaneous monitoring of each compound without the need for additional sample preparation or derivatization. The thermospray spectra for the metabolites exhibited [M + NH4]+ ions and fragment ions because of sequential loss of equivalents of H2O. HPLC/MS showed detection limits in the 0.5 to 5 ng range when using multiple ion detection for most of the metabolites. Post-column derivatization of these metabolites using trimethylanilinium hydroxide (TMAH) to form the methyl esters is also presented. This derivatization resulted in a gain in ion current by a factor of 3-6 for most compounds while adding potential specificity to the analysis. The thermospray spectra of the derivatives were nearly identical to the spectra of the free acid except the peaks were incremented by 14 daltons due to the methyl ester formation. The derivatization of the carboxylic acid group proved to be complete under thermospray conditions producing the maximum ion current and causing no compromise in operation of the interface.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 281-287 
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Fragment ion spectra obtained from collision-induced decomposition of protonated molecular ions have been used to determine amino acid sequences of several physalaemin-like peptides which were recently purified from rabbit stomach. This technique was chosen because the peptides were available in microgram quantities and were anticipated to contain pyroglutamate as the blocked N-terminal residue. Such spectra of several synthetic analogs of the naturally occurring peptides were obtained and analyzed to confirm the veracity of this peptide sequencing strategy. In addition, methyl ester derivatives of these synthetic peptides provided a crucial test for the spectral interpretation via the mass shifts thus induced.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 523-531 
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Derivatization of prostaglandins and thromboxane B2 using diethyl amino ethyl chloride and diethyl amino ethyl bromide improved thermospray HPLC/MS sensitivity. The derivatization was evaluated for prostaglandin A1, A2, D2, E2, F1α, F2α, and thromboxane B2. The derivatization reaction, thermospray operating conditions, and mode of detection were optimized to produce the most intense [M + H]+ or [M - H]- ions for the derivative. Derivatization was better than 99% complete in 1 hour at 75°C. No thermal degradation of the prostaglandins was observed. Positive thermospray ionization proved the mode most sensitive, enabling detection from 10 to 300 pg of each prostaglandin under multiple ion detection. The thermospray spectra exhibited intense [M + H]+ ions for the derivative with a few fragment ions from sequential losses of water from the [M + H]+ ion. Detection of a prostaglandin metabolite in plasma over the concentration range from 3 ppm to 30 ppb was possible using this derivatization.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 0887-6134
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bile from rats treated with acetaminophen was analyzed by direct injection onto a thermospray liquid chromatography/mass spectrometry (LC/MS) system. Two conjugated metabolites of acetaminophen were separated by the high-pressure liquid chromatographic system and analyzed by mass spectrometry. The conjugates were identified as the glutathione-acetaminophen conjugate and the glucuronide-acetaminophen conjugate by comparison of the chromatographic retention times and the mass spectra to that of the synthetic standards. No evidence of acetaminophen metabolites was observed when bile samples were subjected to direct analysis by fast atom bombardment mass spectrometry.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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