Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • 1975-1979  (547)
  • 1970-1974  (428)
  • 1905-1909
  • Analytical Chemistry and Spectroscopy  (975)
  • 1
    Digitale Medien
    Digitale Medien
    A new surface roughening method for glass capillary columns. Sodium chloride deposition from suspension (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 447-455 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Surface roughening by direct deposition of suspension particles ; NaCl used ; High reproducibility when coated with polar phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method is described for roughening the surface of glass capillary columns for subsequent coating with polar stationary phases. A suspension of sodium chloride, obtained by addition of a saturated solution of sodium chloride in methanol to 1,1,1-trichloroethane, is passed through the column at velocities of 1-5 cm/s. During passage of the suspension, particles of sodium chloride deposit spontaneously on the column wall. The amount of sodium chloride deposited on the column wall is a function of the volume of the suspension passed through and of the contact time of the suspension and the column wall. Ultimately the amount of sodium chloride per unit surface area approaches a maximum. Columns covered with this maximum amount of sodium chloride were prepared with high reproducibility and coated with a number of polar stationary phases. Various factors that influence the stability of the suspension and the deposition of sodium chloride are discussed and minimum requirements are given. A theoretical model is proposed for the mechanism of deposition of sodium chloride particles on the glass wall.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020715
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Quantitative evaluation of thin-layer chromatograms. 2. Experimentally confirmed calculations of multilayer models (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 661-666 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Thin-layer chromatography, TLC, HPTLC ; Quantitation ; Theory of, confirmed by experimental results on models ; White background for remission measurements is of advantage ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Multilayer models of different materials were prepared and scanned. Experimental measurements are compared with mathematically predicted values. This comparison leads to a further development of multilayer models. The advantage of using a white background on a scanning table for remission measurements was confirmed by calculation and experiment.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240021104
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Quantitative evaluation of thin-layer chromatograms. 1. The calculation of remission and transmission using multilayer models (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 517-523 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Thin-layer chromatography, TLC, HPTLC ; Photometric scanning ; Radiation transfer equation ; Multilayer model (10 layers) ; Remission ; Transmission ; Sample concentration ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Quantitative evaluation of TLC by direct photometric scanning is a promising method, in view of the development of cheap microprocessors: soon instruments for digital scanning will be commercialy available. In this paper we describe a multilayer model which seems to be a good approximation for solving the radiation transfer equation in the case of layer models with a gradient in an inward direction. Changes of remitted and transmitted light, in cases where a band lies in different layers, are presented. Examples shown are: the absorbance profile of a chromatographed band in the direction of scanning is approximated to that of an isosceles triangle; the concentration of the band is uniform, e.g. 0.3 A. U.; the concentration of the band is changing from 0 to 2.0 A. U. These results will serve to set up the correct algorithms for digital scanning and simultaneous determination in TLC.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020806
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Studies in organic mass spectrometry: XVSande, C. Van de; Vandewalle, M. Bull. Soc. Chim. Belges 1973, 82, 775. - mass fragmentographic identification of epinine in adrenal medulla and as a product of an in vitro enzymic methylation (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 103-108 
    Details
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The presence of epinine in adrenal medulla and in reaction mixtures of enzymic in vitro experiments is proven by mass fragmentography. Derivatization of catecholamines, suitable for gas chromatographic analysis is discussed. The perfluoropropionates were selected for mass fragmentography.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200010204
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Pyrolysis mass spectrometric studies on nucleic acids (1974)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1974), S. 352-357 
    Details
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two different mass spectrometric techniques have been used to analyse the products resulting from Curie-point pyrolysis of nucleic acids: low voltage ionization quadrupole mass spectrometry and high resolution field ionization mass spectrometry. The spectra obtained with both techniques are in good agreement with one another. As already indicated by the low resolution spectra, the high resolution spectra proved that most of the peaks originate from the carbohydrate moiety of the nucleic acid. Micrograms of DNA/RNA can be distinguished very easily by use of these key fragments, although the bases themselves are not found. Some significant pyrolysis mechanisms are proposed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200010512
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Real-time analysis of breath using an atmospheric pressure ionization mass spectrometer (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 6 (1979), S. 91-97 
    Details
    ISSN: 0306-042X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new technique is reported resulting in the direct, instantaneous analyses of trace compounds in breath. The analyses were performed using a commercial atmospheric pressure chemical ionization mass spectrometer (TAGA TM 2000 APCI mass spectrometer). A known flow of breath sample is introduced into the ionization region of the mass spectrometer. The study includes the measurement and monitoring in real-time, of breath ammonia during a 24 hour and a 48 hour period. The ammonia profiles indicate a personalized daily pattern associated with each subject. This method appears to be of potential value in routine detection and treatment of hyperammonemia patients. Results also show that it is possible to obtain instantaneous analyses of several naturally occurring metabolites and other substances on breath in the ppm to ppt range, suggesting a number of diagnostic research applications.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bms.1200060302
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    1H and 13C NMR study of α-acetylenic PIII and PIV derivatives. Signs and magnitudes of J(P—C) and J(P—H) (1975)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 392-400 
    Details
    ISSN: 0030-4921
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: All J(P—H) and J(P—C) values, including signs, have been obtained in acetylenic and propynylic phosphorus derivatives, R2P(X)—C≡C—H and R2P(X)—C≡C—CH3 (X = oxygen, lone pair and R = C6H5, N(CH3)2, OC2H5, N(C6H5)2, Cl) from 1H and 13C NMR spectra. In PIV derivatives the following signs are obtained: 1J(P—C)+, 2J(P—C)+, 3J(P—C)+, 3J(P—H)+, 4J(P—H)—. Linear relations are observed between 1J(P—C), 2J(P—C) and 3J(P—C) versus 3J(P—H), indicating that these coupling constants are mainly dependent on the Fermi contact term, though the other terms of the Ramsey theory do not seem to be negligible for 1J(P—C) and 2J(P—C).In PIII derivatives these signs are: 1J(P—C)- and +, 2J(P—C)+, 3J(P—C)-, 3J(P—H)-, 4J(P—H)+. Only 3J(P—C) and 3J(P—H) reflect a small contribution of the Fermi contact term while in 1J(P—C) and 2J(P—C) this contribution seems to be negligible relative to the orbital and/or spin dipolar coupling mechanisms.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrc.1270070808
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    On the positional interchange of the phenyl- and hydroxyl groups in the [C9H11O]+-ion, generated from 2-methyl-2-phenylpropane-1,3-diol (C10H14O2) upon electron-impact (1973)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 7 (1973), S. 37-43 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is shown by deuterium-labelling experiments, that a substantial part of the [M - CH2OH]+-ions from 2-methyl-2-phenyl-propane-1,3-diol must have rearranged to carbonyl-oxygen protonated phenylacetone by a positional interchange of the phenyl- and hydroxyl groups prior to decomposition.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210070107
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    The Chemistry of C6H6O radical cations: A study of rearrangement reactions of halogen substituted ethyl phenyl ethers (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 474-481 
    Details
    ISSN: 0030-493X
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New experimental data on the rearrangement reaction of various phenoxyethyl halides to give [C6H6O]+· are presented and compared with previous studies so that a coherent picture of this process can be developed. By examining the metastable kinetic energy release for low energy decomposing molecular ions of the phenoxyethyl halides, it has been concluded that formation of [C6H6O] occurs by competitive 1,2 and 1,3 hydrogen shifts from the alkyl carbons to oxygen followed by a rate determining C—O bond cleavage. This is substantiated by the absence of a primary hydrogen isotope effect. For more highly activated molecular ions, a new mechanism comes into play as evidenced by the appearance of a small hydrogen isotope effect. It is postulated that this third mechanism involves transfer of the alkyl hydrogen to the ortho position of the ring by a rate determining 1,5 shift, followed by a 1,3 hydrogen shift from the ortho methylene group to oxygen and rapid C—O bond cleavage. This 1,3 hydrogen shift to oxygen appears to be ‘catalysed’ by the halogen atoms yielding phenol ions. No indications have been found for the formation of tautomeric 2,4-cyclohexadienone ions. Furthermore, highly activated molecular ions produce [C6H6O]+· which can undergo metastable decomposition to lose carbon monoxide. Kinetic energy release measurements for the latter reaction show that the majority of these [C6H6O]+·ions have been formed as phenol ions as well. These arguments are supported by energetic measurements and by comparisons with previous ion cyclotron resonance and collisional activation studies.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/oms.1210140904
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    CIDNP effects in various magnetic fields during the reaction of substituted benzyl chlorides with n-butyllithiumPaper presented at the International Symposium on Chemically Induced Dynamic Polarisation of Nuclei and Electrons, Tallinn, Estonian SSR, 13th to 16th August 1972. (1973)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 5 (1973), S. 599-602 
    Details
    ISSN: 0030-4921
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We detected and studied CIDNP effects in the reaction of substituted benzyl chlorides with n-butyllithium in hexane (Scheme 1) in various magnetic fields (from 0·5 Oe to about 25,000 Oe). The polarisation of 19F nuclei in the reaction of p-F-benzyl chloride in strong fields has been observed by Rakshys.1 We succeeded, however, in finding the CIDNP effects for both 19F and 1H in all the reactions investigated. The CIDNP effects observed offer a number of remarkable features; therefore, a detailed analysis of these effects can be useful for a better understanding of the nature of CIDNP.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrc.1270051211
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...