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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 18 (1984), S. 90-95 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Retention prediction ; Substituted benzenes ; Molecular parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of substituted benzene derivaties on a reversed-phase C-18 column has been examined. The correlations between the logarithm of the capacity factor and several descriptors indicating the molecular size, shape and the physical properties of a solute were determined. The results indicated that hydrophobicity is the dominant factor to control the retention of substituted benzenes. Their retention in reversed-phase HPLC can be predicted with help of the equations derived by multicombination of the parameters.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Liquid column chromatography (reversed phase) ; Inductive effect ; Dispersive effect ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The equation for the potential energy of interactions established for gas-liquid chromatography has been confirmed in reversed phase liquid chromatography. Equations derived for molecular polarizabilities of PAHs and their retention data have very high correlation coefficients. The results indicate that the inductive effect between solute and stationary phase is the main one and the dispersive effect is very small compared with the inductive effect but its contribution increases with the carbon chain length of the stationary phase.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 17 (1983), S. 259-261 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Infrared detection ; Capillary packed columns ; Micro LC systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The performance of a new IR monitoring system was investigated with a fused-silica packed capillary column. The concept of the system is to select solvents which do not have IR absorption at the wavelength where the detector will be operated (e.g., perdeutero-or perhalogeno-compounds) and to use a tefion flow cell. The results show the minimum detectable limit at the submicrogram level for n-hexane and n-dodecane with a short packed capillary column.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenyl bonded phases ; Effect of pore size on retention ; Polycyclic aromatic hydrocarbons ; Silica supports
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Differences in bonded phase properties were studied for triphenyl, diphenyl, phenyl and benzyl phases prepared on a variety of silicas. A total of six silicas with pore diameters ranging from 100 to 200 Å were used in the synthesis. The effect of the pore diameter of the silicas on the retention of polycyclic aromatic hydrocarbons are discussed. Differences in retention were observed as a function of pore size, but not much difference was observed with substrates having pore sizes larger than about 170Å. The observed phenomena are explained by two steric exclusion mechanisms, one during the bonding reaction, and the other in the chromatographic analysis. Statistical calculations were performed using the descriptors showing molecular size and/or shape. The results indicated that the difference between bulky phases and less bulky phases was only observed in the degree of shape-recognition ability of the solute while no differences exist in the retention mechanisms on the different phases.
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention prediction system ; UV multichannel detector ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention prediction system assisted by a micro-computer coupled with an UV multichannel detector has been investigated in the separation of polycyclic aromatic hydrocarbons. The method offered very precise identification of components in NBS-SRM-1647 sample without any standard reference substances. It has been proven that the system makes very precise, non-pollutive and convenient environmental analysis possible.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention correlation ; Silica ; Normal and reversed phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The correlation between the retention data of polyaromatic hydrocarbons (PAH) obtained in normal-and reversed-phase liquid chromatography is investigated in order to determine the dominant factors controlling the retention. It is clear that the separation of PAHs on various chemically-bonded packing materials in normal- and/or reversed-phase modes is primarily controlled by the molecular structure and shape. The π-electron interaction between the solute and the stationary phase also contributes to the retention, although pure silica shows a somewhat different behavior.
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  • 7
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Infrared spectroscopy ; Interfacing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coupling of supercritical fluid chromatography (SFC) and infrared spectroscopy (IR) is growing in popularity. SFC/IR is one of the important hyphenated techniques in modern analytical chemistry. Basically two types of interfacing approaches have been introduced: direct flow cell and solvent elimination. These techniques are reviewed and their advantages and disadvantages are discussed.
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  • 8
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 25 (1988), S. 1004-1011 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Capillary columns ; Open-tubular capillary columns in LC ; Slurry-packed capillary columns in LC ; Packed capillary columns in LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The most recent interest in liquid chromatography (LC) is the trend of column miniaturization, i.e., in reducing the diameter of the columns. Capillary columns used in LC can be classified into three types, based on the flow resistance factor ϕ defined by Knox as $$\phi = d^2 /K_0 = \Delta Pd^2 /\eta \mu L$$ where d is a characteristic dimension of the column (the internal diameter of the tube of the mean particle diameter of the packing), Ko is the specific column permeability, ΔP is the pressure drop along the column, η is the viscosity and μ the linear velocity of the mobile phase, and L is the column length. The first type of LC capillary columns have a ϕ value of about 30. These are theopen-tubular columns, with a retentive film or layer on the inside wall of the column tubing the diameter of which should be as small as possible. The second type of LC capillary columns (ϕ≃100) is made by losely packing a glass tube which is then drawn to smaller diameter. During the drawing process the particles will be partially inbedded into the tube wall. Finally the third type of LC capillary columns (ϕ≃500–1000) are made by slurry-packing 0.2–0.5 mm ID fusedsilica capillary tubes under high pressure. These columns are well packed. In the paper various aspects of these columns are reviewed and their relative performance discussed.
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  • 10
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Planarity recognition ; Monomeric and polymeric ODS phases ; Chracterization ; C-13 NMR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Planarity recognition of polycyclic aromatic hydrocarbons has been investigated using bonded octadecyl stationary phases synthesized in different ways. Retention results indicate apparent differences among the functionalities of the stationary phases, a fact found useful for identifying the functionality of commercially available octadecylsilica (ODS) phases. Retention behevior can be explained by the slit-like structures of polymeric oDS phases, as evidenced by suspension13C NMR measurements.
    Type of Medium: Electronic Resource
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