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  • Liquid chromatography  (6)
  • Chemistry  (2)
  • Chromatoscopy  (2)
  • Quantum optics, physics of lasers, nonlinear optics, classical optics
  • Surface physics, nanoscale physics, low-dimensional systems
  • binary mixtures
  • equation of state
  • 1980-1984  (10)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Physico-chemical applications of liquid chromatography II. Investigations of the surface properties of chemically modified silica gels and of the adsorption of cardiac glycosides from solutions (1981)
    Springer
    Chromatographia 14 (1981), S. 13-18 
    Details
    ISSN: 1612-1112
    Keywords: Chemical modification of silica ; Liquid chromatography ; Cardiac glycosides ; Chromatographic investigation of adsorption from solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chemical modification of silica surface using dichlorosilanes with methyl and phenyl groups and triethylamine as donor in the liquid phase was investigated. This modification leads to a dense coverage of the silica surface by the organic functional groups. Liquid chromatography permits the determination of the thermodinamic characteristics of intermolecular interactions of different molecules during adsorption from solutions on the modified surface of the silica. Silica gels modified with dichlorosilanes containing phenyl groups, possess high selectivity (α) and capacity (k′) for the cardiac glycosides G-strophanthin, K-strophanthoside, K-strophanthin-β and cymarin using water-alcohol mixture as the mobile phase, and the selectivity and capacity is much higher than observed on silica gels modified with methyl groups only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262056
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  • 2
    Electronic Resource
    Electronic Resource
    Regularities in the retention of isomeric aromatic hydrocarbons in liquid chromatography II. Analysis of polymethyl- and monoalkylbenzenes on silanized silica gel (1981)
    Springer
    Chromatographia 14 (1981), S. 638-640 
    Details
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Aromatic hydrocarbons ; Molecular structure ; Influence on retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The regularities of the retention of polymethyl- and monoalkylbenzenes on a nonpolar adsorbent (silanized silica gel) with a polar eluent (2∶3 isopropanol-water) have been studied. In contrast to the retention of the same compounds on a polar adsorbent (silica gel with hydroxylated surface) and with a nonpolar eluent (hexane) polymethylbenzenes are retained on silanized silica gel for a shorter time than the corresponding monoalkylbenzene isomers. The retention order of tert.-, sec.- and n-butylbenzenes is the reverse of that observed on silica gel having a hydroxylated surface. The retention order of xylenes, trimethyl- and tetramethylbenzenes is also the reverse of their retention order on silica gel having a hydroxylated surface. All the mixtures of the corresponding homologues and isomers have been separated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02291103
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  • 3
    Electronic Resource
    Electronic Resource
    Intermolecular interactions in liquid adsorption chromatography (1983)
    Springer
    Chromatographia 17 (1983), S. 143-148 
    Details
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Intermolecular interactions ; Adsorption from solutions ; Chemically modified layers in LC ; Conformation of bonded chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the investigation of intermolecular interactions in adsorption from solution, which are the basis of selectivity in molecular liquid chromatography (LC), it is convenient to use the LC method itself. Using this method the Henry's constants, K1, and other thermodynamic adsorption characteristics of hydrocarbons and of a series of polar substances on hydroxylated silica surface were determined from aqueous solutions. On the basis of the adsorption of hydrocarbons from water solutions the structure of the chemically modifying layers formed by different hydrocarbon groups on the silica surface is considered. The role of conformation ability of straight-chain bonded phases is demonstrated. Hydrocarbons are adsorbed on the hydroxylated silica surface more strongly from aqueous solutions than from solutions in saturated hydrocarbons and their retention increases with the increase in the number of carbon atoms in the molecule. The retention in LC is determined by the intermolecular interaction of the solute and solvent molecules with the adsorbent, as well by the contribution of the intermolecular interaction, between the solute and the solvent. The thermodynamic characteristics of adsorption of cymarin from water-ethanol solutions on hydroxylated silica gel and on silica gel surface modified by diphenylsilyl groups is compared. The solubility of silica gel modified by diphenylsilyl groups at different composition of water-ethanol eluent at different temperatures is investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271037
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  • 4
    Electronic Resource
    Electronic Resource
    Physico-chemical applications of liquid chromatography I. Investigation of the adsorption of cardiac glycosides from water-ethanol solutions on silanized silica (1980)
    Springer
    Chromatographia 13 (1980), S. 745-751 
    Details
    ISSN: 1612-1112
    Keywords: Adsorption from solutions ; Liquid chromatography ; Cardiac glycosides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using the cardiac glycoside cymarin as the example the application of liquid chromatography for the study of adsorption from solutions and the determination of the corresponding thermodynamic characteristics was investigated. The adsorption isotherm of cymarin at small concentrations from a water-ethanol solvent on silica gel modified by dimethyldichlorosilane was measured under static conditions using analytical LC to determine the concentrations of solutions after adsorption. The values of the Henry constants were obtained by extrapolating the slope of the adsorption isotherm down to zero concentration. The specific retention volumes for different but small sample sizes of cymarin in the chromatographic column were measured, the adsorbent and the water-ethanol eluent being the same as in the static conditions. The specific retention volume for a small (zero) sample size determined by liquid chromatography experiment coincides with the Henry constant of cymarin adsorption determined in static conditions. In favourable cases liquid chromatography can be used to determine the equilibrium constants for adsorption from solution. The dependence of the Henry constants on temperature was investigated for several cardiac glycosides. The influence of the modification of the adsorbent surface on the separation of the cardiac glycosides was also studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265553
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  • 5
    Electronic Resource
    Electronic Resource
    Chromatoscopic determination of the geometric parameters of indane hydrocarbon molecules (1981)
    Springer
    Chromatographia 14 (1981), S. 107-109 
    Details
    ISSN: 1612-1112
    Keywords: Gas-adsorption chromatography ; Structure of molecules ; Indane, methylindanes ; Chromatoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A molecular statistical calculation of the retention volumes at zero surface coverage on graphitized thermal carbon black using the atom-atom approximation for the potential energy of intermolecular interaction between adsorbate and adsorbent has been carried out for different structure models of indane, 2-methylindane and 5-methylindane molecules. By comparing the results of the calculations with measured retention volumes, plausible models have been chosen for the structure of the molecules studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02279521
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  • 6
    Electronic Resource
    Electronic Resource
    A chromatoscopic study of fluorene, indenes and styrene (1982)
    Springer
    Chromatographia 15 (1982), S. 245-248 
    Details
    ISSN: 1612-1112
    Keywords: Chromatoscopy ; Gas chromatography ; Graphitized carbon black ; Molecular structure and retention ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A molecular-statistical calculation of the retention volumes at zero sample size on graphitized thermal carbon black is carried out for quasi-rigid molecules of fluorene, indene, 1-methylindene, 2-methylindene and three dimethylindenes. A reasonable agreement is observed between the calculated and the available experimental gas chromatographic data. The potential barrier to internal rotation and the torsional angle in styrene molecules are estimated by comparing theoretically calculated and measured retention volumes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265656
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  • 7
    Electronic Resource
    Electronic Resource
    Liquid chromatography of benzene derivatives on a porous methacrylate copolymer containing epoxy groups (1983)
    Springer
    Chromatographia 17 (1983), S. 545-548 
    Details
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Porous copolymer containing epoxy groups ; Retention of nonpolar and polar benzene derivatives ; Dipole moment and liquid chromatography retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of benzene derivatives with nonpolar and polar substituents on a porous methacrylate copolymer containing epoxy groups using both nonpolar and polar eluents was investigated. When n-hexane is used as the eluent, the retention of n-alkylbenzenes and polymethylbenzenes is weaker than that of benzene. In the case of benzene derivatives containing polar functional groups their capacity ratios (k) on this porous polymer increases approximately linearly with the increase of the adsorbate molecules dipole moment. The retention characteristics of the methacrylate copolymer were compared with that of a styrene-divinylbenzene copolymer and silica gels with a hydroxylated surface and with a surface modified by chemically bonded alkylsilyl groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261917
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  • 8
    Electronic Resource
    Electronic Resource
    Separation of carbohydrates by liquid chromatography on silica gel, adding adsorption modificators to the eluent (1982)
    Springer
    Chromatographia 15 (1982), S. 751-756 
    Details
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Carbohydrates ; Bonded-phase columns ; Silica gel modified with amino groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the separation of carbohydrates by liquid chromatography, utilizing the intermolecular interaction with amino groups on the surface of the adsorbent, two types of adsorbents were used: silica gel modified by adding to the eluent a diamine, and a chemically bonded phase prepared by the reaction of γ-aminopropyl triethoxy silane with silica gel. Mono- di- and trisaccharides could be separated on silica gel modified by the adsorption of piperazin and ethylene diamine from the eluent. The separation capacity of columns packed with silica gel with bonded NH2 groups and with silica gel having diamines adsorbed on its surface is similar. The retention volumes of 15 carbohydrates were measured on columns containing silica gel with hydroxylated surface and on silica gel modified with piperazin from the eluent consisting of acetone-water. Comparison of acetone-water and acetonitrile-water as the eluent showed that the former is also suitable for the analysis of carbohydrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261370
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  • 9
    Electronic Resource
    Electronic Resource
    Reactive polymers, XXXVIII.Part XXXVII: Angew. Makromol. Chem. 95 (1981) 129. Sorption of acid gases on macroporous 2,3-epoxypropyl methacrylate copolymers modified by a reaction with amines (1981)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 96 (1981), S. 69-84 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Aminolyse von makroporösen Copolymeren aus Glycidylmethacrylat und Ethylendimethacrylat führte zu Sorbentien mit einem unterschiedlichen Gehalt an Amino-und Hydroxygruppen. Es wurde die Abhängigkeit zwischen strukturellen Parametern und der Schwefeldioxidsorption auf der einen und der Konzentration des Vernetzungsmittels und der porogenen Lösungsmittel in der Polymerisationsmischung auf der anderen Seite untersucht. Die Schwefeldioxidsorption hängt von der geometrischen Struktur des Sorbens, der Konzentration, der chemischen Struktur und der Erreichbarkeit der funktionellen Gruppen ab.
    Notes: Macroporous copolymers of 2,3-epoxypropyl methacrylate and ethylenedimethacrylate modified by aminolysis yielded sorbents with various contents of amino and hydroxy groups. The dependences of structural characteristics of these sorbents and of the sorption of sulphur dioxide on the content of crosslinking agent and on the cyclohexanol/dodecanol ratio used as the porogenic medium in the preparation of copolymers were investigated. The sorption of sulphur dioxide depends on the geometrical structure of the sorbent, concentration, chemical structure and accessibility of functional groups.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1981.050960106
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  • 10
    Electronic Resource
    Electronic Resource
    Vibrational Spectra of Crystalline Hexachlorocerates(IV), R2CeCl6 (1981)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 474 (1981), S. 233-240 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Schwingungsspektren kristalliner Hexachlorocerate(IV), R2CeCl6Eine vollständige Zuordnung aller Fundamentalbanden in den Spektren kristalliner R2CeCl6, die zu den Ce—Cl-Schwingungen gehören, wurde unter Benutzung von Daten über Kombinationsschwingungen und im Raman-Spektrum aktiver Oberschwingungen vorgenommen. Die Vermutung über die Existenz einer isolierten [CeCl62-]-Gruppe, die in Kristallen mit einer genügend hohen Gitterpunktsymmetrie eine oktaedrische Struktur aufweist, konnte bestätigt werden. Auf der Grundlage des experimentellen Materials und seiner Deutung wird die Vermutung über das Auftreten eines Pseudo-Jahn-Teller-Effektes in der Hexachloroceraten(IV) geäußert.
    Notes: A complete assignment of all fundamentals in the spectra of crystalline R2CeCl6 belonging to the Ce—Cl vibrations was undertaken using data about combination bands and active in the Raman spectrum overtones. The assumption of the presence of a separate [CeCl62-] group possessing an octahedral structure in crystals with a sufficient high site symmetry has been confirmed. Based on the experimental material and its interpretation a presumption concerning the appearence of a pseudo-Jahn-Teller effect in the hexachlorocerates(IV) was supposed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19814740326
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