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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 37 (1993), S. 627-634 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; ODS phases ; NMR and FTIR characterization ; Stationary phase functionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two spectroscopic methods, solid state NMR and diffuse reflectance FTIR, have been used in conjunction with liquid chromatographicretention data to identify and distinguish the functionality of octadecylsilica (ODS) stationary phases. NMR and FTIR spectra are indicative of various features of the different functionalities of the phases and this information can be used to elucidate the configuration of the organosilyl moiety in the ODS on the silica surface and explain why DSS phases have different molecular shape (mainly planarity) recognition capability.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular recognition ; Multidentate phenyl-bonded phases ; PAHs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary New multidentate phenyl-bonded phases (MPBPs) were synthesized and evaluated the chromatographic retention behaviour with polycyclic aromatic hydrocarbons as sample probes in high-performance liquid chromatography. The new MPBPs show different retention characteristics from the previously synthesized MPBP, designated TP. Nevertheless, the results indicate that the retention mechanism is still the same as the TP phase: the size and shape of the solute molecule can be recognized by a cavity-like space formed by the methyl groups and phenyl rings of MPBPs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 35 (1993), S. 38-44 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; On-line and off-line identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of fullerenes with a monomeric octadecylsilica bonded phase using n-hexane or toluene/methanol mobile phase systems is described. Analytical and preparative separations, incorporating on-line UV/VIS spectral measurements, confirmed the existence of large fullerenes such as C76, C78 and C84. However, isomers of C78 and C84 were not conclusively found.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 39 (1994), S. 285-293 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorinated chemically bonded silica ; Aromatic compounds ; Molecular shape vs. retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorinated bonded silica has been evaluated as a packing material in reversed-phase liquid chromatography (RPLC) with polycyclic aromatic hydrocarbons, chlorinated benzenes and substituted benzenes as sample probes. The bonded material is useful as a reversed-phase stationary phase and for polar compounds it offers a specific selectivity not found with octadecylsilica (ODS) phases. The phase also retains non-planar compounds more than planar molecules. The results can be explained by conformational differences between ODS and the fluorinated bonded phase by MM2 calculation.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; Octadecylsilicas ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of column temperature, especially at low temperatures, on the separation of fullerenes on monomeric and polymeric octadecyl silica (ODS) bonded phases has been studied. Decreasing the column temperature induces an increase in selectivity. The best temperature for the separation of fullerenes was determined for both types of ODS phase with n-hexane eluent. The selectivity for higher fullerenes on monomeric phases becomes similar to that on polymeric phases to low temperature. It has been found that as the carbon content of monomeric phases is increased, the selectivity also becomes similar to polymeric phases.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 30 (1990), S. 51-56 
    ISSN: 1612-1112
    Keywords: Reversed-phase liquid chromatography ; Computer-assisted prediction system ; Peptide sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer-assisted prediction system for small peptide sequencing has been constructed based on the retention prediction approach in reversed-phase liquid chromatography. The system has the basic function to predict retention of small peptides at any chromatographic conditions and this function can be useful for the prediction of sequencing. The outline of the system construction and the performance is discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1612-1112
    Keywords: Chromatography, general ; Optimization ; Information theory ; Kalman filter ; Retention prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper treats optimization problems involving unresolved component peaks with the information measure FUMI (Function ofMutualInformation) as a criterion. The LC analysis of 20 PTH-amino acids is taken as an example of the optimization of mobile phase composition, column length and temperature. The quantitative structure-retention relationship is adopted for the simulation and for the establishment of feasible solutions of the problems. The applicability of the FUMI theory is further extended by solving the above optimization problems.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 31 (1991), S. 448-452 
    ISSN: 1612-1112
    Keywords: Column dead-time ; Supercritical-fluid chromatography ; Cyclodextrin stationary phase ; van der Waals' surface area ; van der Waals' retention factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical relationship between retention time and the van der Waals' surface area of solute molecules has been investigated for the members of a homologous series. In the case of two homologous series, n-alkanes and alkylbenzenes, the validity of this relationship was experimentally verified on a supercritical-fluid chromatographic column packed with β-cyclodextrin. A new chromatographic parameter, the van der Waals' retention factor, is also defined. The solute retention time in the investigated systems was found to be a linear function of the van der Waals' retention factor. The relationship led to a new definition of the column dead-time, and was found to be the retention time of a hypothetical solute with “zero” van der Waals' surface area. Using this linear relationship the column dead-time can be determined. The retention data of the two homologous series obtained under identical experimental conditions gave very similar values for the column dead-time.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl modified silica ; Hexamethyldisilazane treated silica ; Calcination ; Heat-treated silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of silanol groups on three types of octadecylmodified column gels using heat-treated silicas by calcination has been studied by high-performance liquid chromatography. After heat-treating at 180°C, 500°C and 950°C, the silicas treated with octadecyldimethylchlorosilane were used for the measurement of physical and chemical analysis. From elemental carbon analysis data, the reactive silanol group concentrations, αOH(s), were determined to be 2.0 in the 180°C treated silica, 2.1 in the 500°C treated silica and 1.6 in the 950°C treated silica, respectively (original silica: mean pore diameter 116 Å, specific surface area 298 m2/g, pore volume 1.22 ml/g, particle size 5.0 μm). The separation factors, α, of pyridine versus phenol were measured to be 0.79 on 180°C treated silica, 0.91 on 500°C treated silica and 1.98 on 950°C treated silica, using acetonitrile-water mixtures as the eluent. And then, on the basis of the physico-chemical and chromatographic data, the three types of octadecyl modified column gels using heat-treated silicas by calcination have been compared.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column void volume ; Cyclodextrin stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A brief critique on the existing methods for the determination of LC column dead volume is presented. The dispute and controversy among scientists regarding the definition of column void volume, as well as the methods for its determination are pointed out. Difficulties arising in connection with the determination of the dead volume of cyclodextrin columns are discussed; it seems that the applicability of conventional methods is questionable. The necessity for further research in this field is stressed.
    Type of Medium: Electronic Resource
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