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  • 1990-1994
  • 1980-1984
  • 1975-1979  (668)
  • 1979  (668)
  • Physics  (588)
  • Gas chromatography
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 7 (1979), S. 227-234 
    ISSN: 1434-0879
    Keywords: Oxalic acid ; Acid metabolites ; Urine ; Back-flushing ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The known methods of oxalic acid determination are not suitable for reliable, rapid and economical routine analysis. A rapid gas chromatographic method has been developed which dispenses with separation operations and measures oxalic acid as a diethylester by means of back-flushing, and using malonic acid as an internal standard. One determination can be conducted within 6 to 8 min. and preparation of the specimen takes about the same amount of time. If the gas chromatographic conditions are changed and more time is permitted for analysis, numerous other extractable acidic metabolites can also be determined.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 42 (1979), S. 257-268 
    ISSN: 1432-1246
    Keywords: Phenol ; Cresols ; Gas chromatography ; High pressure liquid chromatography ; Photometry ; Urine ; Phenol ; Kresole ; Gaschromatographie ; Hochdruckflüssigkeitschromatographie ; Photometrie ; Harn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine gaschromatographische und eine hochdruckflüssigkeitschromatographische Methode zur Bestimmung von Phenol und Kresolen im Harn wind beschrieben. Phenol wind in beiden Fällen selektiv erfaßt. o-, m- und p-Kresol wird beschrieben. Phenol wind in beiden Fällen selektiv erfaßt. o-, m- und p-Kresol werden hochdruckflüssigkeitschromatographisch nicht getrennt. Gaschromatographisch gelingt die Abtrennung von o-Kresol. Aufgrund der speziellen Probenaufbereitung sind beide Verfahren sehr empfindlich. Die Nachweisgrenzen liegen zwischen 0,2 und 1,3 mg/l. 24-h-Harne eines Normalkollektivs (n = 30) werden untersucht (xPhenol = 4,6 mg/l; xp-Kresol = 45,7 bzw. 52,6 mg/l). Die Ergebnisse werden mit denen eines photometrischen Verfahrens verglichen.
    Notes: Summary Gas chromatographic and high pressure liquid chromatographic methods for the determination of phenol and cresols in urine are described. In both cases phenol is determined specifically; o-, m- und p-cresols are not separated by high pressure liquid chromatography. However, o-cresole is separated by gas chromatography. On account of the special preparation of urine samples both methods are very sensitive. The detection limits lie between 0.2 and 1.3 mg/l. 24-h samples of normal urines (n = 30) are analysed (xphenol = 4.6 mg/l; xp-cresol = 45.7 mg/l, respectively 52.6 mg/l). These results are compared with those of a photometric method.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 790-798 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Dead-time ; log ts=f(C) ; Retention index calculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird eine Methode zur Retentionsindex-Bestimmung beschrieben, die von einem kubischen Zusammenhang zwischen Bruttoretentionszeit-Differenzen der Referenzhomologen und der Kohlenstoffzahl ausgeht. Hieraus ergeben sich direkt die Nettoretentionszeiten. Der Fehler der Totzeitbestimmung entfällt bei dieser Methode. Mit den so gewonnenen Nettoretentionszeiten erhält man über einen kubischen Zusammenhang zwischen 1g ts=f(C) die Retentionsindices. Extrapolationen und Interpolationen sind über 300 Retentionsindexeinheiten mit einem mittleren Fehler von ±0,02 Retentionsindexeinheiten möglich. Das Verfahren bietet sich für eine automatische Berechnung der I-Werte mittels on-line-Datenverarbeitung an.
    Notes: Summary The method for the calculation of retention indices described here is based on a third order relationship between the logarithm of differences of unadjusted retention times of homologues and the carbon number. From this adjusted retention times are directly calculated. A determination of the dead-time is not necessary thus avoiding the errors connected with this factor. A cubic equation for the logarithm of the adjusted retention time lg ts as a function of carbon number Cn is used for the retention index calculation. Extrapolations and interpolations can be done over a range of 300 index units with an average deviation of ±0.02 i.u.. The method offers the possibility of an automated on-line calculation of retention indices by computer merely on the basis of unadjusted retention times.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 523-526 
    ISSN: 1612-1112
    Keywords: Amantadine ; Gas chromatography ; Gas chromatography-mass spectrometry ; Biochemical analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, selective and sensitive method for the quantitation of amantadine in biological samples is described. After extraction from biological samples using a two-step procedure, amantadine is quantitatively converted into its isothiocyanate (NCS) derivative by treatment with carbon disulfide and then determined quantitatively using isobaric compounds, p-methoxyphenyl-ethylamine-NCS or N-acetylamantadine as external standards. The applicability of this method is illustrated by determining plasma levels of amantadine for pharmacokinetic studies and levels in dialysate samples of amantadine treated patients who were on dialysis machines.
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  • 5
    ISSN: 1612-1112
    Keywords: Polynuclear aromatic hydrocarbons ; Retention index ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An equation has been derived allowing to predict retention index values on nematic phases from computable parameters and sizes of the molecules of polycyclic aromatic hydrocarbons. Another equation, which has also been derived, allows to determine the shape parameter of a molecule from chromatographic data.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 583-586 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Clinical analysis ; Meningitis detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas liquid chromatography was performed on cerebrospinal fluid from cases of purulent meningitis, and control subject. A relatively constant pattern of peaks was obtained in all samples. Four constant peaks in the chromatogram frequently showed a significant increase in purulent meningitis but not in aseptic meningitis or control cases. There was a gradual return to normal levels during clinical improvement, usually within 5–6 days of appropriate therapy. In one case of recurrent meningitis, an increase in the peaks was noted with relapse. Identification of the compounds represented by these peaks may provide further information regarding diagnosis, prognosis and pathogenesis of meningitis.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International ophthalmology 1 (1979), S. 109-122 
    ISSN: 1573-2630
    Keywords: Photocoagulation ; Non-linear effects ; Physics ; Morphology ; Nd glass Q-switched laser ; Scanning electron microscopy ; Chamber angle ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Working at a power density above optical breakdown threshold, irradiation effects upon the angle of the anterior chamber of the Macaca speciosa monkey by a Nd glass Q-switched laser, have been analysed with scanning electron microscopy. Two different damage effects can be identified: openings of Schlemm's canal and the creation of a cyclodialysis, that is opening the uveoscleral outflow routes; the latter may be a more effective one than the former. Also a third mechanism, namely a structural alteration of the trabecular meshwork, at the molecular level by laser action, has been inferred. The physical effects leading to optically induced mechanical damage are discussed. Applicability of such effects upon the morphological findings described here, is limited and to a greater part speculative. A better definition of the physical parameters, required for optimal therapeutical damage effects in the treatment of the wide angle glaucoma may be obtained by trial and error methods, which are guided by the results of electron microscopical analyses of samples obtained from in vivo and in vitro experiments.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 168-170 
    ISSN: 1612-1112
    Keywords: Acid catalyzed esterification ; Amino acids ; Fatty acids ; Gas chromatography ; Isopropyl esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acid-catalyzed esterification of carboxyl groups with acetyl chloride in isopropanol is investigated. Yields are equivalent to those obtained with reagent prepared conventionally by bubbling gaseous hydrogen chloride into isopropanol. The preparation of the former reagent is less time consuming and no special equipment is needed. The procedure is applicable for other alcohols as well.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 533-538 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sorbents: liquid phases, supports, adsorbents ; Thermodynamical classification ; Polarity and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Equations modifying Rohrschneider's relationship between ΔI and thermodynamical characteristics values are derived. Polarity in chromatography is discussed as a possibility of stationary phases or absorbents to enter into intermolecular interactions and is determined on the basis of the partial molar free energies of solution (ΔG) of six test substances. A simple method for the calculation of stationary phase polarity in terms of ΔG from retention indices and McReynolds constants is given. Equations are presented for the calculation of stationary phase selectivity utilizing ΔG data tabulated for selected test substances. The thermodynamical basis of selecting a reference phase for a unified system expressing the selectivity of stationary phases which can also be applied for adsorbents is suggested. The energy equivalent to an index unit, ΔGi.u., is discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 803-807 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ionization detector ; High frequency discharge ; Specific or no specific detection ; Gas adsorption (by flues)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The response of a high frequency ionization detector according to various parameters: voltage, tuning capacitance, feed-back capacitance, space between the electrodes and direct flux-plasma distance is studied. The characteristic measure of v in accordance to high voltage for various mixtures of carrier gas argon-nitrogen gives a maximum which demonstrates that specific automatic analyses of oxygen, krypton and methane are possible with concentrations in the order of ppb. Complete adsorption of 0.8 ppb of methane by a flue of 120 cm in tube 2×4 mm at 50°C after twentieth recycling is essential.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 530-532 
    ISSN: 1612-1112
    Keywords: Hexetidine ; Triamine ; Gas chromatography ; On-column interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatography was used for the direct assay of hexetidine and triamine in a pharmaceutical formulation. During this work we came across a strong oncolumn interaction, in such a way that the GLC retention, selectivity and response parameters were seriously modified relative to the injections of hexetidine and triamine standard solutions. The interaction was traced to the coinjected hydrochloride form of a major component of the sample and in practical terms points to the potential quantitation errors that may be associated to similar systems.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 665-671 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index ; Multiple correlation ; Molecular properties ; Prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein auf der linearen, multiplen Korrelation basierendes Verfahren wird vorgestellt, das es gestattet, den Retentionsindex von Substanzen in der gaschromatographischen Trennung aus einem Satz Säulenkonstanten und drei bis vier Substanzeigenschaften zu berechnen. Der Fehler der Berechnung liegt unter 2%. Der Ansatz wurde für isothermes und temperaturprogrammiertes Arbeiten getestet.
    Notes: Summary A method based on linear multiple correlation is introduced allowing the calculation of gas chromatographic retention indices from a set of column constants and three to four physical properties of the solute. The error is less than 2%. The formulation has been tested for isothermal and temperature programmed working conditions.
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  • 13
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Porous polymer supports ; Retention behaviour-effect of support
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatographic behaviour of a series of compounds of different polarity on columns of Ethofat 60/25 on Chromosorb P HMDS (an inactive support) and Chromosorb 101 (an active support) was investigated. To observe how the support influences the chromatographic process, we separated the contribution to the retention volume of the interaction phenomena associated with the stationary phase, the solid support and the corresponding interfaces. In some cases the Chromosorb 101 exerts an influence on the process even with high percentages (〉10%) of stationary phase. The values of the experimental partition constants of a series of compounds and the factors that contribute to adsorption on these columns are calculated.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 733-736 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas volume, influence of ; Preconcentration ; Wine headspace analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Examination was made of the changes in composition of aroma volatiles trapped on Chromosorb 105 during dynamic headspace sampling of aged wine. Collections from different gas volumes were analysed and a subsequent collection made. It was demonstrated that analyses of headspace collections containing reduced quantities of the more volatile and more, hydrophobic compounds could aid in the identification and quantitative determination of alcoholic beverage components.
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  • 15
    ISSN: 1612-1112
    Keywords: Inclusion compound ; Urea-cetylalcohol adduct ; Gas chromatography ; Clathration process ; Phase changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Phase changes in urea-cetyl alcohol inclusion compounds prepared by various methods were monitored gas chromatographically. The decomposition temperature interval and the presence of the free components could be found from the temperature dependence of the retention data. Study of the clathration process yielded facts that can be used in the preparation of this type of inclusion compound.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 265-270 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Columns: open tubular ; Columns: capillary ; Efficiency ; Mean specific plate number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new parameter, the mean specific plate number, is proposed for assessing the efficiency of support coated open tubular (SCOT) and wall coated open tubular (WCOT) columns and for comparing the efficiency of different open tubular columns. It has the advantage over most previously used parameters in that it has only a small dependence on the partition ratio and it allows for the column diameter. A graphical presentation is given of the maximum theoretical mean specific plate number as a function of the partition ratio for SCOT columns having a range of relative porous layer thicknesses and for WCOT columns with a range of phase ratios. This presentation permits ready visual comparison of the potential efficiency of different columns and enables a simple evaluation of the percentage utilization of theoretical efficiency from experimentally determined values of the maximum mean specific plate number. For a given column the percentage utilization of theoretical efficiency at optimum average gas velocity and that at optimum practical gas velocity or at a higher average gas velocity are shown to be equal provided that corrections for column pressure drop are made.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 463-466 
    ISSN: 1612-1112
    Keywords: Hydrothermal treatment of Porasils ; Adsorption properties ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple modification was employed by thermal or hydrothermal treatment of silica gel (Porasil). In this way chromatographic materials with advantageous properties were prepared. The changes of the adsorbent under different thermal and hydrothermal treatment were studied in more detail. The experimental results show that under controlled conditions material with required chromatographic properties can be prepared.
    Type of Medium: Electronic Resource
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  • 18
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ethanolamines ; Ethylene glycols ; Porapak Q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary GC separation of pure ethanolamines as well as mixtures with ethylene glycols, obtained from a real technological process is achived using Porapak Q coated with 15% Carbowax 20M. Symmetrical peaks, satisfactory resolution, and reasonable analysis times are obtained. The proposed method is suitable for a convenient, correct and express routine analysis.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 509-515 
    ISSN: 1612-1112
    Keywords: Optimization ; Carrier gas velocity ; Gas chromatography ; Influence of temperature on optimum velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The selection of the average linear carrier gas velocity in the analysis of a multicomponent mixture under isothermal and programmed-temperature conditions is discussed. It is shown that one shouls always select a velocity which is at least equal but preferably higher than the optimum average gas velocity of the earliest peak at the initial column temperature.
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  • 20
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index calculation ; lg ts=f(C) ; Dead-time ; Complex mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die bisher in der Literatur beschriebenen Verfahren zur Retentionsindex-Bestimmung beruhen auf einem linearen Zusammenhang zwischen dem Logarithmus der Nettoretentionszeit lg ts und der Kohlenstoffzahl C der n-Alkane. Wie genaue Meßwerte für Retentionszeiten zeigen, ist die Funkton lg ts=f(C) nicht streng linear. Die Krümmung des Funktionsbildes bedingt, daß lineare Regressionsmethoden, sowie auch die Methode nach Kovats, es nicht erlauben, extrapolativ sowie über weite Retentionsbereiche interpolativ I-Werte zu berechnen. In dieser Arbeit werden Retentionsindices aufgrund eines kubischen Zusammenhanges zwischen lg ts und der Kohlenstoffzahl ermittelt. Die hierzu notwendige Totzeit tm wird aus den Differenzen der Bruttoretentionszeiten der Referenzhomologen ermittelt.
    Notes: Summary Methods of retention index calculation described in the literature have been based on a linear relationship between the logarithm of the adjusted retention times lg ts and the carbon numbers C of n-alkanes. Exact measurements of the retention times of n-alkanes show that the relationship lg ts=f(C) is in fact not strictly linear. Correct extrapolative or interpolative calculations of retention indices over a wide retention range are therefore impossible when using the original formula as given by Kovats or methods based on a linear regression concept. The method of retention index calculation presented here is based on a cubic relationship between lg ts and carbon number allowing extrapolative or interpolative calculations. The hold-up time (tm) is calculated on the basis of differences of retention times of the reference homologues.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 12 (1979), S. 89-94 
    ISSN: 1612-1112
    Keywords: Determination of HCl ; Derivatization ; Trace analysis ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird die Möglichkeit untersucht, kleine Mengen HCl durch derivatisierung mit 7-Oxabicyclo-(4.1.0)-heptan und anschließendem gas-chromatographischen Nachweis des Reaktionsproduktes 2-Chlorcyclohexanol zu bestimmen. Die Nachweisgrenze für das Produkt der Derivatisierung (2-Chlorcyclohexanol) entspricht 2 pg HCl. Durch verschiedene Probleme, die im Rahmen dieser Arbeit diskutiert werden, wird diese Nachweisgrenze in der Praxis nicht erreicht. Es zeigt sich jedoch, daß HCl-Konzentrationen im Bereich von ppm (bzw. HCl-Mengen〈1 μg) ohne weiteres zu bestimmen sind. Die Möglichkeiten dieser Analysenmethode werden diskutiert.
    Notes: Summary This paper the possibility of determining small quantities of HCl by derivatization with 7-oxabicyclo-(4.1.0)-heptane and subsequent gas chromatographic identification of the reaction product 2-chlorocyclohexanol is examined. The detection limit for the derivative (2-chlorocyclohexanol) is equivalent to 2 pg HCl. On account of various problems, discussed in the paper, this detection limit is not achieved in practice. It is nevertheless apparent that concentrations of HCl in the ppm-region (quantities of HCl〈1 μg) can be determined without difficulty. The scope for this method of analysis is disscussed.
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  • 22
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Columns: open tubular ; Columns: capillary ; Columns: capillary: comparison ; Efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detailed comparison is given of the various equations derived by Golay and that derived by Hawkes for assessing the theoretical efficiency of SCOT columns. The terms in these equations which describe the resistance to mass transfer in both the gas phase and in the liquid phase are given in a form which permits the equations to be compared directly. A numerical comparison is then made of the potential efficiency predicted by the different equations for five partition ratio values for a set of nine idealized SCOT columns with a wide range of porous layer thickness and liquid loading. The potential column efficiencies are expressed in terms of the maximum theoretical mean specific plate number. It is shown that appreciable differences occur between the theoretical efficiencies given by the different equations when the porous layer thickness and liquid loading are high, but these differences are small for most of the columns used in practice.
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  • 23
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 288-292 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Stationary phases, polar, gum type ; For temperatures up to 300°C ; For most of the common classes of organic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Most of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ∼50° to ∼300°. High MW Superox-4 has a MAOT about 20° higher than the lower MW Superox-0.1. Several applications illustrating the versatility of Superox phases in (GC)2 are presented.
    Additional Material: 9 Ill.
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  • 24
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 429-435 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface roughening by diatomaceous support (5 micron particles deposition) ; Organic glue (polar polymethacrylate acetate) used as intermediate material ; Reproducibility and durability of capillaries discussed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A technique for adhesion of fine particles (ca. 5 μ) of the 405 white diatomaceous support on the inner wall of glass tube with organic glue [poly (diethylaminoethyl methacrylate) acetate] is described. The coated tube was drawn to capillary column by using a machine designed according to Desty's. The capillary column was then coated with stationary phase (such as squaiane, QF-1, Dexsil 300, PEG 20 M, OV-1, SE 30 and etc.) by the conventional dynamic or static method. This preparation method has proved easy to duplicate and is simple. The coating efficiency (UTE %) is within 60-90. The theoretical plate number per meter of an SE 30 column is about 4000, and per meter of a PEG 20 M column is about 2500. The columns thus prepared have been successfully used to analyze petroleum hydrocarbons, essential oils, petrochemicals, pheromone, steroid metabolites and others.
    Additional Material: 6 Ill.
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  • 25
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 635-636 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Cyclandelate quantitation ; In plasma. No sylilation needed ; Analysis within 16 min, range 5-50 ng/mikroliter ; Correlation coeff. 0.996 (N=6) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 26
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 177-183 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary ; Injection by tailored capsule-insertion technique ; Critical comparison with split-injection technique ; Competitive with best-known systems ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A capsule-insertion system tailored to the needs of capillary gas chromatography is described. It provides the basis for a truly quantitative and improved qualitative approach to open tubular capillary GLC. The advantages of the system lie in its simplicity of handling and in the possibility of using relatively low injection temperatures, thus reducing the risks to thermally unstable samples.The observed high efficiencies characterizing this capillary GLC capsule technique allow full advantage to be taken of the operating capacity of the superior capillary columns to give a performance competitive with the best known split-injection systems.
    Additional Material: 11 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 254-254 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Hydrodesulphurization products elution ; Room temperature two-column operation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 28
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 283-287 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Sampling technique ; Semi-automation of head space sampling ; Application to water pollution, coffee aroma, light hydrocarbons in crude oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Head space GC using a special electropneumatic sampling system works well in combination with glass capillaries. Because a homogenous gas mixture is already present most problems inherent with inlet splitters are thus avoided. In cases where the high vapor pressure of the sample can cause problems with the pressure controlled sampling system, the use of narrow bore glass capillaries provides the necessary inlet pressure. The use of this powerful and convenient analytical tool for water pollution analysis, flavour analysis and the analysis of volatiles in crude oil samples is shown by examples.
    Additional Material: 5 Ill.
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  • 29
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 319-323 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Mobile phase flow programming ; Comparison with temperature programming ; Short capillaries offer considerable shorter analysis time when flow programmed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique of programming the carrier gas flow rate in gas chromatography, especially in connection with the use of capillary columns shorter than 10 m can significantly accelerate GC analyses. Equations for calculation of the parameters of the exponential flow function and retention data are described. The effects of flow programming in a short capillary column are shown in a few chromatograms. Different programming rates are tested and compared with temperature programming.
    Additional Material: 7 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 297-302 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface roughening ; Amorphous silica ; Deactivation ; Column performance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the preparation of wall-coated glass capillary columns after surface roughening by means of amorphous silica is described. After the glass capillary has been leached, a small quantity of amorphous silica is deposited evenly on the inner surface. This is done by passing a plug of dilute water glass through the capillary, followed by a flow of gaseous hydrochloric acid. The roughened surface is stabilized, deactivated and finally coated.This paper furnishes details of the technique and information about the performance of a number of columns prepared by the method.
    Additional Material: 5 Ill.
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  • 31
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 324-328 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Theory in contrast to traditional approaches ; Very practical formulas for peak width, maximum load, concentration in mobile phase ; Optimizing procedure for trace analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to traditional theoretical approaches by calculation of (nonexistent) theoretical plates, a unified theory of gas chromatography as given by a definition of the resolution analogue to methods in signal processing or spectroscopy using the well-known Kovacz indices as fundamental scale. A derivation of the thusly defined resolution from basic physical principles yields very practical formulae for peak width, maximum load, substance flow in peak maximum, concentration of substance in the carrier gas and other interesting parameters in dependence of capillary diameter, capillary length, film thickness, carrier gas speed, viscosities etc. Diagrams show favourite conditions for detectors responding on absolute substance flow (e.g. FID) or on concentrations.
    Additional Material: 4 Ill.
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  • 32
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 400-404 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Low temperature plasma etching ; Polymer film on the inner surface from organosilicone monomer ; Flexibility of this new method discussed ; Discharge chamber described ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC2). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.
    Additional Material: 8 Ill.
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  • 33
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 416-422 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; SECAT-technique=stepless fine tuning of capillary selectivity by serial column temperature optimization ; Exponential influence of temperature on selectivity over a wide range found ; SECAT-technique ready for automation of column adjustment on sample composition polarity ; Instrumental and methodological details for primitive self made solution given ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: GC, including capillary GC, is rather inflexible, if a certain column length and stationary phase has been fixed for a given analytical problem. If the sample composition changes, one often has to change the column length and/or stationary phase, at least when something like optimum analytical conditions are needed. Temperature changes (or heating rates) can change the selectivity of a given column only within very limited ranges, due to the exponential effect of temperature on retention time. By serial coupling two chemically different capillaries, each run at another temperature, even the slightest changes of these two temperature values have a dramatic effect on the selectivity of the system for polar substances. We call this technique the SECAT mode of GC. Results are reported as retention index shifts, dependent on SECAT temperature data. This technique can in future easily be automated, thus enabling the analyst, for polar sample analysis, to adjust a given chroma-tographic system to his specific sample composition without touching the instrument.
    Additional Material: 7 Ill.
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  • 34
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 487-496 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Comparison of FID, ECD, FPD for detection limit. linearity, peak shape etc. ; Practical results for pesticide residue and coal hydrogenation products given ; Concentration dependent detectors in capillary GC interesting, when optimized ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparison of the characteristics and Performance of the flame ionization, electron capture, and flame photometric detectors with capillary columns is described. Factors which may affect the limits of detection, linearity, chromatographic peak shape, and other detector performance characteristics are discussed and compared with the results of a model derived for the behavior of concentration and mass flow-rate dependent chromatographic detectors used with capillary GC systems. Examples are given of highly complex and labile mixtures such as pesticide residues and products from coal hydrogenation.
    Additional Material: 13 Ill.
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  • 35
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 581-582 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Retention indices and substituent constants ; Phenols ; Polar stationary phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 36
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface deactivation, persllylation ; Discussion of variable parameters ; Suggested practical procedure ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 37
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 629-630 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary glass ; Nitrogen-specific detection ; TMSN ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 38
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 31-35 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface deactivation, silylation ; Inertia stable to 350° ; Free acids and bases, simultaneous injection ; On-column injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A deactivation procedure is described based on a published method using hexamethyldisilazane in the gas phase. In addition to unusually high inertia and thermostability, the method produces truly neutral columns which allow simultaneous analysis of moderately strong free acids and bases. The silylated columns show their full potential only with on-column injection. Preliminary experimental directions are given; more elaborate directions will become available after extended optimization work.
    Additional Material: 3 Ill.
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  • 39
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 529-530 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Requirements with respect to pressure controllers ; Design of pressure controllers ; All-metal controllers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 40
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 186-186 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Carrier gas ; Flow control by flattened tube restriction ; Fine tuning by adjustable twisting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 41
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 187-188 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Whiskers, OV-17 ; Steroid profiling ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 42
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 357-360 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Whisker production ; Violent explosion at the „ether etching“ step ; Modification of pyrex glass etching leads to more uniform whiskers in size and shaep, simple, safe ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent attempts to reproduce a literature method for etching of Pyrex glass capillary columns with „etching ether“ resulted in reduction of the columns to dust through a violent explosion. Although modifications of the method produced etched columns, we found that less than satisfactory results were achieved. Introduction of etching ether by simply coating the column with a thin film of the ether produced an evenly etched column with well defined whiskers. Several observations made during the etching process will also be discussed.
    Additional Material: 3 Ill.
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  • 43
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 361-365 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Sample preparation by pre-chromatographic reaction at the 7 microliter level ; Reproducibility of methylation and allylation of barbiturates ; Application to blood analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pre-chromatographic reactions are no longer a necessary evil. Equipment such as the microrefluxer now allows reproducible 7-μl-reactions to be carried out in a short time. Thus multiple derivatisations can be used together with glass capillary GC for routine identifications. The method has been succesfully applied to barbiturates. Retention data of their methyl-, allyl- and benzyl-derivatives are given.Quantitative blood level determinations are briefly discussed.
    Additional Material: 6 Ill.
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  • 44
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 411-415 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Enantiomer amino acids separated on chirally functionalized polysiloxane phase ; McReynolds constants of chiral phase given ; HCl gas pretreatment, colloidal silicic acid deposition best wall preparation ; Racemisation tested ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillaries coated with Chirasil-Val, a chirally functionalised polysiloxane, are capable in principle of resolving all protein amino-acid enantiomers in a single run and within a short analysis time, thus allowing for example the quantitative amino acid determination by enantiomer labelling. The elution characteristics of the individual amino acids however are also dependent upon the chemical nature of the capillary wall surface, and a surface pretreatment is found to be necessary if all protein amino acids are to be analysed. Of the various methods of pretreatment tested, etching of borosilicate glass with gaseous HCl followed by deposition of colloidal silicic acid is considered to be the most suitable.
    Additional Material: 2 Ill.
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  • 45
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 436-440 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; „bo“ data (starting peak width) in valveless multidimensional operation studied ; Heart cutting, trapping, re-injection effects measured ; Band broadening caused by connections small (160 ms2) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to permit valveless MDSS operation and easy column change, the hardware designed contains several connections. These can give rise to extra-column band broadening effects. In order to quantitate such effects, the packed-capillary column configuration (without trap) was used. The band broadening caused by the connections was found to be small: 120 ms2. A more practical approach was used to check the performance of the trap (re-injection) in the capillary-trap-capillary column configuration. Here the results obtained with re-injection from the trap were compared with results obtained in transfer and heart-cutting modes while the trap was heated. Re-injection was tested with n-alkanes ranging from n-C6 to n-C28. A starting peak width of 1.6 s was found.
    Additional Material: 5 Ill.
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  • 46
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 456-460 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary ; Theory ; Linearity between peak width and retention data ; Evaluation of GC equipment ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The linearity of the relationship between σT,t2 and (1 + k)2 is studied with the view of using it for the evaluation of GC equipment. Based on appropriate analytical expressions it is concluded that in general this relationship is not linear and that practical procedures for column evaluation should be developed that take this non-linearity into account.
    Additional Material: 3 Ill.
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  • 47
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 461-474 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Limitations by temperature, in trace analysis, by irreversible adsorption ; Sample capacity, separation efficiency ; Multidimensional GC advantageous ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillary gas chromatography is a high resolution separation method which allows the qualitative and quantitative analysis of even complex mixtures, which may contain many components-also isomeric-in a wide range of volatilities, polarities and concentrations.The principal limitation of gas chromatographic application is given by an insufficient volatility of the species to be separated. Elevated temperatures have to be applied if the application range is to be extended and to achieve steep peak profiles, i.e. low detection limits at high resolution. The use of elevated temperatures is limited, of course, by the temperature stability of both the solvent (stationary liquid and support) and the solutes.The problems of trace analysis for low volatility compounds at high resolution and its limitational parameters regarding sampling, separation and detection are discussed.The applicability of glass capillary columns in this field is influenced by the following parameters: tailing behaviour; irreversible adsorption of polar and decomposition of unstable solutes; thermal stability of stationary liquid (including the support deactivation); separation efficiency and sample capacity (film thickness).Multidimensional gas chromatography using capillary columns coupled either with a packed or another capilllary column for preseparations may be applied with advantage in the analysis of complex mixtures.
    Additional Material: 7 Ill.
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  • 48
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 527-528 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Leaching compared to etching ; Leaching by 20% HCI at 240°C ; Metal ions eliminated from glass surface ; Silica layer formed on leached surface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 49
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 712-714 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Cholesteric liquid crystal phase ; Separation of geometrical isomers ; Cholesteryl cinnamate ; Insect pheromones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 50
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 72-73 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary ; Split injection problems even at ratios 1:100 and 0.06 ml injection ; Band broadening effects, leading tail caused by reverse solvent effect for early peaks rel. to late solvent peak ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 51
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 303-311 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Overview, preparation and evaluation techniques ; Quantitation is the least satisfactory aspect of (GC)2 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 7 Ill.
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  • 52
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 405-410 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Stationary phases of polysiloxane-type degrade in acidic solution ; Several salt traces affect stability at high temperature NaCl on Duran-5O: no effect at 260°C ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of polysiloxanes have been shown to be sensitive to acids when dissolved in chloroform.At 26O°C polysiloxanes were found to degrade under the influence of several compounds used or produced during the preparation of glass capillary columns.
    Additional Material: 6 Ill.
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  • 53
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 577-578 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; support and packing production technique and device ; drying, removal of fines, silanization, solution coating, total evaporation ; in one system ; normal transport results in partial mechanical partlkel damage, causing tailing, decomposition on uncoated surfaces ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 54
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 221-224 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary ; Vapor-phase sampling ; Sample preparation, extraction by carbon dioxide under high pressure, Freon 12 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new sample preparation procedures that produce solvent-free extracts especially suitable for use with high resolution GC are described. One is based on Soxhlet extraction in a pressurized container that permits the use of liquid carbon dioxide as the extractant; the other utilizes refluxing difluorodichloro-methane (Freon 12) to isolate entrained volatiles from gas streams.
    Additional Material: 6 Ill.
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  • 55
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    Journal of High Resolution Chromatography 2 (1979), S. 216-220 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, at 25O°C ; Sampling via precolumn enrichment ; Precolumn backflush, reinjection after trapping the volatiles ; Rejection of non-volatiles ; Automation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel sampling system for isothermal capillary gas chromatography of medium- or low-volatility mixtures is described and test results are reported using flame ionization detection. The system features a loading and positioning chamber for glass vials which can carry a dilute sample in up to 0.2 ml of a volatile solvent. The output from the glass vaporization chamber is trapped onto a packed precolumn operated in the backflush mode. The analytes are further transferred over a wall-coated capillary trap prior to isothermal capillary GLC. Repeat-cycle operation of the sampling system requires 10 channels of a processor for time control over 5 solenoid valves and 3 static heaters. Preliminary results with long-chain n-alkanes in the submicrogram range showed no unwanted effects. The principal claim of the system is an improved rejection of non-volatiles.
    Additional Material: 3 Ill.
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  • 56
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    Journal of High Resolution Chromatography 2 (1979), S. 249-250 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Deactivation stable up to 35O°C ; High temperature phase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 2 Ill.
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  • 57
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    Journal of High Resolution Chromatography 2 (1979), S. 378-384 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Glass capillaries for low volatile polar natural products analysis ; Application to N-TFA-dipeptide, TMS-ribose, TMS-manno-samin, peptide sequence analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two published procedures for glass capillary column production are applied to produce capillaries for chromatography of polar natural compounds. Soda lime glass capillaries, after leaching with aqueous HCL, are either treated with colloidal silicic acid or with barium carbonate and coated with either Silar 7CP or SE 52. A test mixture as well as polar carbohydrate and peptide mixtures are chromatographed on the different columns and their chromatographic properties are evaluated. Combined capillary gas chromatography-electron impact and chemical ionization mass spectrometry are used for identification of the peptide sequence.
    Additional Material: 8 Ill.
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  • 58
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    Journal of High Resolution Chromatography 2 (1979), S. 444-446 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Micropacked columns ; Sample capacity under comparable conditions forty times larger than in capillaries ; Equations given ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equations have been derived from which the maximum sample size which may be loaded on a column without significantly affecting the performance may be calculated. It is shown that micro-packed columns can handle a sample which is as much as forty times larger than that which can be loaded onto wall-coated open tubular columns with comparable conditions.
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  • 59
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    Journal of High Resolution Chromatography 2 (1979), S. 481-486 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Splitting conditions for quantitative sampling investigated ; Injection amount and temperature should remain constant ; Standard deviation below 1% ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sample inlet splitters are used in capillary column gas chromatography. We have investigated the sample band broadening in the splitter and studied reproducibility and accuracy in quantitative analysis using a simple lab-made splitter. It was found that the results were dependent upon the operating conditions such as split ratio, splitter temperature, glass wool plug, injected sample volume and solvent.
    Additional Material: 7 Ill.
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  • 60
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    Journal of High Resolution Chromatography 2 (1979), S. 423-428 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, nickel ; „Transevaporator“ into packed pre-column as sampling technique prior capillary described ; Application to volatile metabolite body fluid analysis for early detection of disease ; Serum and human breast milk as examples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nickel capillary columns coated with moderately polarstationary phases such as Witconol can be used for the separation of the organic volatile fraction from biological fluids. A “transevaporator” sampling technique for the collection of the organic volatiles on glass beads from as little as 5 to 500 μl of biological fluids (e.g. urine, serum, amniotic fluid, breast milk, saliva, etc.) is described. The organic volatiles are thermally desorbed from the glass beads into a short precolumn cooled in liquid nitrogen, which overcomes the problems associated with sample introduction onto narrow-bore capillary columns. The application of the full analytical technique to problems associated with the early detection of disease is illustrated.
    Additional Material: 5 Ill.
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  • 61
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    Journal of High Resolution Chromatography 2 (1979), S. 441-443 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Methodological and instrumental solution of the recirculation problem ; In-line miniature switching valves used ; Column length optimization possible ; Over 3500 theoretical plates per second generated ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multiple repass system, utilizing an in-line switching valve and suitable for use with small-bore glass open tubular columns, is described. The advantages of the system, which include higher OPGV, large plate numbers and optimization of column “length”, are discussed.
    Additional Material: 5 Ill.
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  • 62
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 475-480 
    ISSN: 0935-6304
    Keywords: 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
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 7 Ill.
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  • 63
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Packed columns ; Glass transition temperatures of 3 polymers ; Polystyrene ; Poly(vinyl chloride) ; Poly(methyl methacrylate) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The glass transition temperatures, Tg, of polystyrene, poly (vinyl chloride) and poly(methyI methacrylate) have been determined from gas chromatographic measurements using n-hexane, n-heptane, meta-xylene and para-xylene solvents. The glass transition temperatures were detected on the z-shaped retention diagrams which were produced from the plot of the logarithm of the specific retention volumes of the above-mentioned solvents against the reciprocal of temperature, i.e. log Vgº vs. 1/T. The glass transition temperature is specified by the temperature where the slope of log Vgº vs. 1/T changes abruptly. The observed glass transition temperature of polystyrene produced by this technique was found to be in good agreement with those produced by other techniques such as the differential scanning colorimeter.The industrial importance of the glass transition temperature, Tg, might be due to the dramatic changes in the physical properties of the polymer, such as hardness and elasticity, which take place in the vicinity of this temperature. However, perfectly crystalline polymers do not exhibit glass transitions, because their chains are incorporated in regions of three-dimensional order, called crystallites. Completely amorphous polymers and semi-crystalline polymers usually exhibit both glass transition and melting.
    Additional Material: 3 Ill.
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  • 64
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 536-539 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Photoionization detector ; Detector cell volume contribution to band broadening ; Flow rate effects on volumetric-based peak variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 65
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 580-580 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; support and packing production device ; drying, removal of fines, solution coatig, total evaporation ; principal virtue of the system: solvent can be recovered ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 66
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 715-719 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Sample introduction ; Direct manual operation at the capillary inlet ; Micro pipette is coupled onto cold separation capillary ; PTFE connection used ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
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  • 67
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Separation of polychloro biphenyls ; Separation of organochlorine pesticides ; Splitless automated injection ; Residue level ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complicated PCB mixtures can be separated in individual compounds using glass capillary gas chromatography, (GC)2. Depending on extraction and clean-up procedure it is also possible to separate and determine organochlorine pesticides at the same time.This (GC)2 technique can be used to determine the contents of individual chlorinated biphenyls in milk products and animal feedstuffs and in the analysis of complicated extracts of soil and vegetable material.Practical aspects concerning connection of the capillary, automatic splitless injection, repeatability of the retention time, quality of the column with respect to separation and adsorption and degradation of DDT are discussed.The detection of individual chlorinated biphenyls is possible at the ppb level in fats and vegetable materials, using an extraction and clean-up procedure, based on saponification of the sample.Preliminary results for milk, obtained from several areas, are shown.
    Additional Material: 6 Ill.
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  • 68
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    Journal of High Resolution Chromatography 2 (1979), S. 746-748 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Pt/Ir tubing ; Interfacing and coupling of columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
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  • 69
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 312-318 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Subnanogram analysis of estrogens as heptafluorobutyric esters ; ECD, quantitative analysis, automatic injection ; Run-to-run precision at the 50 picogram level between 2 and 7% rel. standard deviation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Subnanogram detection of steroids has become increasingly important today. One applicable method for gas chromatographic determination of subnanogram quantities of estrogens as halogenated derivatives is electron capture detection. HFB-derivatives of 7 different estrogens were automatically injected onto a prolonged narrow bore wall-coated glass capillary column. Normal split injection could not be used for this trace analysis because of too much loss of sample. Only small amounts of sample were available from which double analysis had to be performed.Cross-contamination of the automatic sampling system as well as precision of retention times and peak areas were determined.The type of injection described showed better quantitative results compared to the splitless injection technique.All details of the system used together with the results are this discussed in this paper.
    Additional Material: 3 Ill.
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  • 70
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    Journal of High Resolution Chromatography 2 (1979), S. 343-350 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Analysis up to C50 in GC/quadrupole MS combination ; No special procedures necessary when using commercially available instruments ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of low volatile compounds by (GC)2/MS using high-temperature stable glass-capillary columns and a commercially available GC/quadrupole MS instrument is described.It will be shown that no special modifications or procedures are required in analyzing organic compounds exceeding carbon numbers of 50. The application to industrially and naturally occuring high boiling mixtures will be discussed.
    Additional Material: 9 Ill.
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  • 71
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    Journal of High Resolution Chromatography 2 (1979), S. 351-356 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Potash soda lead and fused silica as wall material investigated ; Thin-walled fused silica is an ideal material ; Inherently more inert than normal glass ; High flexibility avoids fragility problems ; Application examples (alcohols, mercaptanes, sulfides, phenolsamines, acids) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An investigation was conducted of various glasses, other than soda lime or borosilicate, for use in glass capillary gas chromatography. The work has uncovered some unique chromatographic qualities in the use of potash soda lead and fused silica glasses as materials for making glass capillary columns. The fused silica proved to be an ideal material for capillary column construction, being inherently more inert than glass containing metal oxides. It has been shown that through the use of thin wall capillary tubing of high flexibility many of the mechanical problems associated with glass capillary columns, such as fragility and column straightening, can be avoided.
    Additional Material: 7 Ill.
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  • 72
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    Journal of High Resolution Chromatography 2 (1979), S. 366-370 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Sampling problems by syringe needle temperature ; Technical solution of the problems by cooling and heating up minimized masses ; Discrimination and standard deviation measured with test mixtures C18-C38 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On-column injection into a hot gas chromatograph oven involves the danger that the bottom part of the needle is warmed up above the boiling point of the solvent in the sample. Consequently parts of the sample are evaporated out of the needle instead of being introduced as a liquid into the capillary column. This causes losses and hence discrimination of the less volatile parts of the sample which remain in the needle.A technical solution is proposed using a system for cooling the capillary during the injection, down to the injection point in the oven.
    Additional Material: 2 Ill.
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  • 73
    ISSN: 0935-6304
    Keywords: 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
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
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  • 74
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    Journal of High Resolution Chromatography 2 (1979), S. 749-750 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Packed column, glass ; Dichloroacetic acid ; In biological fluids, at 50 ng level ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 2 Ill.
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  • 75
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    Journal of High Resolution Chromatography 2 (1979), S. 293-296 
    ISSN: 0935-6304
    Keywords: 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
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 6 Ill.
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  • 76
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    Journal of High Resolution Chromatography 2 (1979), S. 329-334 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Theory ; Systematic treatment of simplification effects on minimum plate height and optimum carrier gas velocity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Band broadening in capillary columns is satisfactorily described by the Golay-equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically.
    Additional Material: 4 Ill.
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  • 77
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    Journal of High Resolution Chromatography 2 (1979), S. 335-342 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Two-dimensional technique ; Critical evaluation of individual instrumental components ; Minimization of extra column effects and operational parameters discussed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A versatile two-dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off-line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra-column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown.
    Additional Material: 4 Ill.
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  • 78
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    Journal of High Resolution Chromatography 2 (1979), S. 395-399 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Retention index determination, reproducibility and error propagation ; Retention time measurement of ±0.01% necessary for retention index reproducibility of ±0.05 units ; Error propagation calculation program for pocket calculator given (HP 67) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Precise evaluation of the chromatographic data by means of the relative retention will allow the full use of the resolution achieved by capillary columns. In practice, retention-index determination is best suited for this purpose. The reproducibility of retention-index determination strongly depends, among other factors, on the accuracy of retention time measurement. A reproducibility of ±0,05 i.u. can be easily achieved with modern gas chromatographic equipment, provided the retention times can be measured with an accuracy of at least ±0.01%. This can be shown by error propagation analysis of retention-index calculation performed with the aid of a programmable pocket calculator.
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  • 79
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    Journal of High Resolution Chromatography 2 (1979), S. 533-534 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Flow stabilization ; Gas velocity in micro-apertures ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 80
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Organic gas phase cigarette smoke ; Microprocessor-controlled ; Cryogenic preconcentration trap ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An automatic injection system for the analysis of gas phase smoke has been designed and evaluated using the microprocessor-controlled Hewlett-Packard 5830 gas chromatograph. The cryogenic preconcentration trap was constructed from relatively inexpensive and readily available materials. It was determined that the use of the preconcentration trap, as opposed to condensing the smoke on the head of the cold (-50°C) chromatographic column, significantly enhanced the resolution of the more volatile gas phase components. Data are presented which illustrate the injection system characteristics. In addition, chromatograms of gas phase smoke are presented which demonstrate the effectiveness of this technique.
    Additional Material: 8 Ill.
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  • 81
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    Journal of High Resolution Chromatography 2 (1979), S. 578-579 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Hydrogen carrier gas ; Laboratory safety ; Leakage detection with a gas monitor ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 82
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 1-23 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new calculation of the vibrational frequencies of poly(ethy1 ethylene) based on the actual molecular geometry was performed. The calculation takes into account new experimental data such far-infrared spectra and Raman spectra of the stretched polymer, infrared spectra of poly(ethyl ethylene)-(2,2;d2) (P-4-1-d2) and poly(ethyl ethylene)-(3,3,4,4;d4) (P-4-1-d4), and Raman spectra of poly(ethyl ethylene)-(1,3,3;d3) and poly(ethyl ethylene)-(3,3,4,4;d4). Refinement produced a set of force constants; it is also applicable to poly(propyl ethylene).
    Additional Material: 4 Ill.
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  • 83
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The vibrational analysis of modification I of poly(propyl ethylene), poly(propyl ethylene)-(2,2;d2), and poly(propyl ethylene)-(1,2,2;d3) has been performed using the valence force field derived for poly(ethyl ethylene) and the actual molecular geometry. The band assignments are based on infrared polarization and Raman data.
    Additional Material: 6 Ill.
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  • 84
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 55-62 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nucleation and growth of the crystalline core in the row structures of isotactic polystyrene were investigated by transmission electron microscopy. The number of core crystals, nucleated at a specific temperature, depends on the external strain. Their length was found to increase with time if the sample is kept at the straining temperature. If a strained sample is cooled to room temperature and subsequently reheated, no further growth of the core crystals is observed. Obstacles in the path of growth were circumvented by local changes of the growing direction. Melt-soluble noncrystallizable molecules are rejected by the growing core into the surrounding melt. The observations suggest a growth mechanism of the cores based on the successive self-induced alignment of molecules at the tip of the growing cores.
    Additional Material: 5 Ill.
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  • 85
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 45-53 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carbon-13 spin-lattice relaxation times (T1), nuclear Overhauser enhancements (NOE), and resonance linewidths (Δp) have been measured for a series of terephthalic acid polyesters containing ethyl, butyl, hexyl, and isopropyl groups between neighboring terephthalate units. The relaxation parameters of all carbons in the terephthalate groups are independent of the length of the separating alkyl chain. Reduced NOE's are seen for all carbons. The data are interpreted in terms of a log X2distribution of correlation times of constant width, but variable average mobility. The average mobility in the alkyl chain increases with increasing distance from the terephthalate group in a given polymer. For a given position in the chain. mobility increases with increasing chain length. This behavior is consistent with the presence of independently reorienting, highly solvated terephthalate groups.
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  • 86
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 73-79 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polytetrafluoroethylene (PTFE) was extruded from a capillary rheometer at temperatures between the first-order transition at 30°C and the melting point. Both PTFE at 50-300°C and various smectic states of certain low-molecular benzylidene anilines obey the following relationship between the shear stress τ and the apparent shear rate $ \dot \gamma :{\rm }\tau = K\dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} $. The apparent viscosities for the two classes of substances are similar even though their molecular weights differ by a factor of about 104. Both have characteristic shear planes which are parallel to the polymer chains in PTFE and normal to the long axes of the benzylidene aniline molecules. The melting process in virgin PTFE begins near 300°C. Above this temperature, the shear stress at constant shear rate increases and the rheological exponent rises from 0.25 toward 0.5 at the final melting point.
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  • 87
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    Journal of Polymer Science: Polymer Physics Edition 17 (1979), S. 63-71 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent experiments have supported the view that polyethylene (PE) single crystals kept in suspension, in a variety of liquids, have different physical properties compared with the same crystals after drying. The present work was undertaken in an attempt to directly measure one of the basic properties of crystals in suspension, namely their percent crystallinity (X). Differential scanning calorimetry was chosen as the primary tool for this investigation. A method has been developed to determine the weight of PE in a suspension of crystals in a nonsolvent. Thus, a determination of X can be made. For suspension crystals, X was found to be at least 88.5%, some 6% larger than that for the corresponding dried or freeze-dried material. Implications with regard to the fold-surface structure are discussed. Differences in degree of crystallinity as a function of drying procedure have also been observed.
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  • 88
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 19-26 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of methyl methacrylate photosensitized by several alkyl ketones has been investigated. It was found that alkyl ketones can induce the free radical polymerization of the monomer with an efficiency that increases when the triplet lifetime decreases. For ketones of similar triplet lifetime those decomposing predominantly by a type I photocleavage show greater initiation efficiencies than those that react by a type II mechanism. The results obtained show that quenching of the excited ketones by the monomer does not induce polymerization. For ketones bearing γ-hydrogens the initiation is due to the 1,4-biradical produced by intramolecular hydrogen abstraction.
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  • 89
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 49-58 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of γ irradiation on a series of vinyl polymers, which included polymethacrylonitrile, poly(α-chloroacrylonitrile), poly(dimethyl itaconate), poly(acrylic anhydride), and poly(methacrylic anhydride), was studied as part of a program to develop improved positive lithographic resists. Radiation-induced degradation was observed for polymethacrylonitrile, poly(α-chloroacrylonitrile), and poly(methacrylic anhydride). Molecular weight degradation as a function of dose was monitored by membrane osmometry or GPC techniques. For γ-irradiated poly(dimethyl itaconate) and poly(acrylic anhydride) crosslinking was found to predominate over chain scission. [G(s)-G(x)] values, calculated from molecular weight inverse versus dose curves, indicate that both nitrile polymers degraded more efficiently than a poly(methyl methacrylate) reference standard on the basis of Mn changes. The radiation behavior of the first three polymers confirms earlier findings than vinyl polymers with quaternary carbons predominantly degrade when subjected to ionizing radiation.
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  • 90
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 97-109 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The triethylamine-initiated polymerization of glycine-NCA [N-carboxylic acid anhydrides (oxazolidine-2,5-diones)], L-alanine-NCA, and sarcosine-NCA, as well as the pyridine-initiated polymerization of sarcosine-NCA, were carried out in the presence of potential cocatalysts. The 11 electrophilic reagents tested in this work can be divided into two classes: N-acyllactams and similar compounds, which are less reactive than the monomers and have no influence on the polymerization; and isocyanates and N-acyl-NCAs or -NTAs [N-thiocarboxylic acid anhydrides (thiazolldine-2,5-diones)], which are more electrophilic than the monomers and behave as cocatalysts in the case of glycine-NCA and alanine-NCA, since their base-initiated polymerization proceeds via the attack of NCA anions on the electrophilic N-acyl NCA chain and (“activated monomer mechanism”). In the case of sarcosine-NCA, however, the propagation involves a nucleophilic chain end (“carbamate mechanism”) and the strong electrophilic reagents behave as inhibitors.
    Additional Material: 2 Ill.
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  • 91
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 139-145 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of poly(vinyl chloride) (PVC) with superoxide anion was carried out in tetrahydrofuran (THF) at 40°C in a nitrogen atmosphere. Remarkable changes in infrared (IR) spectra of the samples treated with superoxide anion were observed in the following regions: ca. 3300, 1680, 1620, and 765 cm-1, which suggested the formation of hydroxyl groups, α,β-unsaturated ketone groups, and ethylenic structures. Ultraviolet-visible spectra also showed the formation of polyene structures. The content of chlorine in the polymer decreased and that of oxygen increased with reaction time. The reaction mechanism was discussed on the basis of these results.
    Additional Material: 2 Ill.
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  • 92
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 155-162 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To determine the content of trans-gauche-trans (TGT) conformation in poly(ethylene glycol) (PEG) 1H-NMR spectra were measured with tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-1,4,6-octanedinato)europium(III) [Eu(fod)3] as a shift reagent. As a result the peaks assigned to the ethylene protons in the polymeric segments separated from those assigned to four ethylene protons as the “near-end” groups, and the singlet peak in the former at the lowest field was assigned to the TGT conformation of the COCCOC sequence. It was confirmed that the conformation of the polymeric segments in PEG complexed with Eu(fod)3 remained unchanged with benzene-d6 content as the solvent. The concentration of TGT conformation increased with the number-average molecular weight (Mn): it increased rapidly until about 70% at Mn = 1500.
    Additional Material: 7 Ill.
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  • 93
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 173-184 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: γ-Ray-induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low-molecular-weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose-rate dependence of the polymerization rates were different between the two states. Wide-line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ-irradiated FMMA and 1,1′-ferrocenyl-di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.
    Additional Material: 9 Ill.
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  • 94
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 215-224 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was found that carbon disulfide copolymerizes with N-(β-cyanoethyl) ethylenimine by using water as a catalyst. The copolymerization was conducted in detail by using water as a catalyst in the temperature range between 0 and 50°C with various initial concentrations of carbon disulfide and N-(β-cyanoethyl)ethylenimine in the absence of solvent. The copolymer obtained was always composed of the two monomers: 1:1 ratio, independent of the initial concentration of the monomers. The copolymer was white solid material soluble in dimethyl sulfoxide, insoluble in other usual organic solvents and decomposed at 155°C. Spectroscopic analysis of the copolymer combined with the results of elemental analysis indicates that the copolymer had the following structure:
    Additional Material: 8 Ill.
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  • 95
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 267-269 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 96
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 255-266 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alternating polyampholytes (MA-VA) containing two acidic groups and one basic group were prepared by the copolymerization of maleic anhydride (M1) and N-vinylsuccinimide (M2) at 60°C with AIBN as the initiator, followed by acid hydrolysis with 1N hydrochloric acid at 140°C for 24 hr. The monomer reactivity ratios r1 and r2 are 0.025 and 0.06, respectively. The structure of polymers was discussed on the basis of the data of their elementary, infrared (IR), and thermal analyses and the binding ability of heavy metal ion. Polyampholytes were soluble in strong acidic and basic media but were precipitated in the pH range 3-4. An isoelectric point at pH 3 was determined by potentiometric titration and the turbidimetric method. By thermal treatment above 205°C the polyampholyte turned quantitatively into a cyclized lactam. This suggests that the polyampholyte MA-VA has an intramolecular hydrogen bond between the amino and γ-carboxyl groups. The binding of Cu2+ and Hg2+ by the polyelectrolyte was evaluated by equilibrium dialysis.
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  • 97
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 203-213 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex multistage decomposition mechanism was observed which involves two major reaction pathways. Initial degradation occurs by an ionic decomposition process that results in the evolution of tetrahydrofuran. This is followed by concerted ester pyrolysis reactions that involve an intermediate cyclic transition state and yield 1,3-butadiene. Simultaneous decarboxylation reactions occur in both decomposition regimes. Finally, the latter stages of polymer decomposition were characterized by evolution of CO and complex aromatic species such as toluene, benzoic acid, and terephthalic acid. Activation energies of formation for the main pyrolysis products were determined from the dynamic measurements of the major ion species and indicate values of E = 27.9 kcal/mole for the production of tetrahydrofuran and E = 49.7 kcal/mole for the production of butadiene.
    Additional Material: 7 Ill.
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  • 98
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 225-236 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article deals with studies of the dilute solution properties of methyl methacrylate-acrylonitrile (MMA-AN) copolymer of 0.415 mole fraction (mf) of acrylonitrile composition. Mark - Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2-butanone (MEK), dimethyl formamide (DMF), and γ-butyrolactone (γ-BL). The Mark-Houwink exponent a in all four solvents at all temperatures is larger than the corresponding values of the parent homopolymers. The solvent power is in the order of DMF 〈 γ-BL 〈 MEK 〈 MeCN; [η] decreases with an increase in temperature, which is behavior characteristic of polymers in good solvent. The unperturbed dimensions (K0) values, obtained by the Stockmayer-Fixman method, are lower than those for the parent homopolymers and depend on solvent as well as temperature. The solute - solvent interaction parameter X1 values are close to 0.5; X1 is independent of temperature. The excess interaction parameter XABvalues are negative. The results for this copolymer system in regard to low second virial coefficient A2, large X1, and high a values suggest that the large extension of these copolymer chains is due to the unusual short-range interactions.
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  • 99
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 245-254 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (2-Ethyl-2-methyl-1,3-dioxolan-4-yl)methyl- and (2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl acrylates were synthesized and polymerized. The photochemical behavior of the resulting polymers was investigated to determine whether the polymers pending on the 1,3-dioxolane structure were readily crosslinked with ultraviolet (UV) irradiation. The degree of crosslinking was estimated by the weight-loss method by immersion in acetone, with the result that the polymer with an aromatic substituent was more photocrosslinkable than the polymer that bore the aliphatic substituent. The catalytic effect on photocrosslinking of polymers was also studied by using benzoin and cobalt naphthenate. The infrared (IR) spectra of polymers irradiated in air that showed the new band at 3450 cm-1 were attributed to a hydroxyl group; however, the spectra of polymers irradiated in vacuum displayed little absorption at 3450 cm-1. To explain the mechanism of crosslinking model compounds were prepared and irradiated with UV light. It was concluded that crosslinking proceeds mainly from the fission of the 1,3-dioxolane ring and the coupling of the yielding radicals, together with autooxidation by atmospheric oxygen.
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  • 100
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    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 281-286 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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