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  • Artikel  (56)
  • Physical Chemistry  (43)
  • Gas chromatography  (13)
  • Wiley-Blackwell  (56)
  • 1975-1979  (56)
  • 11
    Digitale Medien
    Digitale Medien
    Advances in the preparation and evaluation of GC capillary columns (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 303-311 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Overview, preparation and evaluation techniques ; Quantitation is the least satisfactory aspect of (GC)2 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of (glass) capillary columns of high quality is still not without difficulties. Six problems in this context are highlighted. Column material choice(l), glass wall modification(2) and coating(3) are considered to have reached a satisfactory level. Deactivation(4) is still in a state of flux. Quantitation(5) is the least satisfactory aspect of capillary GC. Scope expansion(6) will be helped by the introduction of new phases of high thermal stability and by the adoption of solutions exclusively applicable to capillary GC.Evaluation of (glass) capillary GC columns is a rapidly developing field. Hopefully the number and complexity of test or polarity mixtures will not expand much further and it will be possible to make a clear and generally acceptable choice.The preparation and evaluation of ever-improving capillary columns is important to an ever-widening group of chromatographers. Our opinion on selected topics in this already vast field is summarized in the following overview.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020610
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  • 12
    Digitale Medien
    Digitale Medien
    Increased thermostability of non-polar wall-coated open tubular columns (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 249-250 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Deactivation stable up to 35O°C ; High temperature phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method of deactivating the inner surface of glass capillary columns is described, which can be used at 350°C without detoriation. A non-polar liquid phase was prepared from a commercially available liquid phase which, when coated on a glass surface, can withstand temperatures of 325°C for isothermal analysis and 350°C for temperature-programmed analysis.After deactivation, the column was coated using the static coating method. Then it was conditioned, tested and kept for 48 hours at 35O°C before being used for the analysis of a mixture of chlorinated pesticides.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020512
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  • 13
    Digitale Medien
    Digitale Medien
    Analysis of nitrosamines by GC2 with a photoionization detector (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 475-480 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Photoionization detector (PID) ; Detection limit 50 to 100 pg nitrosamines at 10.2 eV ; Nitrosamine analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The use of a photoionization detector (PID) coupled to a glass capillary gas chromatography (GC2) separation system for the detection of carcinogenic nitrosamines was investigated. The components analyzed gave a linear response with a lower detection limit of 50 to 100 pg with the 10.2 eV ionization source. No detector response was obtained with an ionization energy of 9.5 eV.Chromatography of meat extracts indicated their complex molecular composition. Simple liquid chromatographic cleaning procedures significantly decreased the complexity of these samples, but not sufficiently for the accurate quantition of nitrosamine components.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020718
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  • 14
    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
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  • 15
    Digitale Medien
    Digitale Medien
    Determination of dichloroacetic acid in plasma and urine (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 749-750 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Packed column, glass ; Dichloroacetic acid ; In biological fluids, at 50 ng level ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method for the measurement of dichloroacetic acid in plasma or urine has been developed. The method involves extraction of dichloroacetic acid into diethyl ether, evaporation of the etheric phase to a small volume and derivatization with diazomethane. Trichloroacetic acid was used as an internal standard. Concentrations as low as 50 ng/ml can be determined.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240021211
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  • 16
    Digitale Medien
    Digitale Medien
    Gas-liquid chromatography of serum bile acids using glass capillary columns (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 293-296 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillarym, glass ; Complete separation of bile acids in serum from cholesterol ; Analysis time less than 15 min, adaptable to GC/MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The proposed combination of a rather simple procedure for sample preparation with capillary gas-liquid chromatography using a barium carbonate/polyethyleneglycol 20,000 column and a Grob-type on-column injector permits measurement of bile acids in serum with high separation efficiency, short analysis time and complete separation of bile acids from cholesterol. The method can be adapted to combined capillary gas-liquid chromatography - mass spectrometry.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020608
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  • 17
    Digitale Medien
    Digitale Medien
    Kinetics and mechanisms of substitution reactions with sulfur-containing nucleophiles in aqueous acid solutions. I - rates of reactions of some tetrahalopalladate (II) anions with thiourea and selenourea (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 87-98 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The activation energy parameters for the reaction of PdX42- (X=Cl-, Br-) in aqueous halide acid solution with thiourea (tu) and selenourea (seu) have been determined. High rates of reaction parallel low enthalpies and appreciable negative entropy of activation. The rate law in each case simplifies to kobs=k[L] where L=tu or seu, and only ligand-dependent rate constants are observed at 25°C. The ligand-dependent rate constants for the first identifiable step in the PdCl42- + X system is (9.1±0.1) × 103 M-1 sec-1 and (4.5±0.1) × 104 M-1 sec-1 for X=tu and seu, respectively, while for the PdBr42- + X system it is (2.0±0.1) × 104 M-1 sec-1 and (9.0±0.1) × 104 M-1 sec-1 for X=tu and seu, respectively.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550070110
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  • 18
    Digitale Medien
    Digitale Medien
    On the fast addition reactions of BH3 (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 633-636 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550070412
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  • 19
    Digitale Medien
    Digitale Medien
    An absolute measurement of the rate constant for t-butyl radical combination (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 8 (1976), S. 45-58 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constant for tert-butyl radical recombination has been measured near 700°K by the very-low-pressure pyrolysis (VLPP) technique and was found to be 108.8±0.3 M-1·sec-1 with neglibible temperature dependence. The thermochemical parameters for tert—butyl radicals were varied within reasonable limits to bring into agreement the data for the decomposition of 2,2,3,3-tetramethyl butane and the recombination of tert-butyl radicals. The revised thermochemistry also makes the gas-phase results and liquid-phase results compatible.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550080107
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  • 20
    Digitale Medien
    Digitale Medien
    Kinetics of the Diels-Alder addition of acrolein to cyclohexa-1,3-diene and its reverse reaction in the gas phase (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 8 (1976), S. 641-649 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Diels-Alder addition of acrolein to cyclohexa-1,3-diene has been studied between 486 and 571°K at pressures ranging from 55 to 240 torr. The products are endo- and exo-5-formylbicyclo[2.2.2]oct-2-ene (endo- and exo-FBO), and their formations are second order. The rate constants (in l./mole · sec) are given by \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} {\rm}k_{{\rm endo}} = -(19,470 \pm 50)/4.576T + (5.65 \pm 0.02)$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} {\rm}k_{{\rm exo}} = - (20,630 \pm 50)/4.576T + (5.51 \pm 0.02)$$\end{document}The retro-Diels-Alder pyrolysis of endo-FBO has also been studied. In the ranges of 565-638°K and 6-38 torr, the reaction is first order, and its rate constant (in sec-1) is given by \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} {\rm}k_{{\rm p}} = - (46,390 \pm 110)/4.576T + (12.98 \pm 0.04)$$\end{document}The reaction mechanism is discussed. The heat of formation and the entropy of endo-FBO are estimated.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550080502
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