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  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Packings of octadecylated microporous glass ; Dimethadione and trimethadione in serum ; Pancreatic stones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase diphenyl and naphtylethyl bonded phases ; Retention/molecular polarizability relationships ; Peropyrene aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of 15 peropyrene-type polycyclic aromatic hydrocarbons was investigated on various bonded stationary phases in reversed-phase liquid chromatography. On diphenyl and naphthylethyl bonded phases, high correlations were obtained between the molecular polarizability of solutes and their retention. However, very low or no correlations were found on various octadecyl bonded phases. These facts are discussed by using the electrostatic interaction concept between the solutes and the stationary phase. We conclude that these observations are due to two reasons: the difference in the degree of planarity of polycyclic aromatic hydrocarbons and the high ability of planarity recognition of octadecyl bonded phases.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 21 (1986), S. 467-472 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded stationary phases ; Phenyl-modified glasses ; Antiepileptic drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention and selectivity behaviour of some antiepileptic drugs were studied by micro high-performance liquid chromatography on nine types of phenyl-modified glasses, prepared with xylene solution containing phenyldimethylchlorosilane (P), diphenylmethylchlorosilane (D) or triphenylchlorosilane (T), using three types of glass with various mean pore diameters and/or specific surface areas. From elemental analysis data for carbon, the maximum number of accessible phenyl surface groups per 100Å2 of glass (mean pore diameter: 335Å, specific surface area: 69m2/g) in P, D and T gel was calculated to be 2.38, 1.58 and 0.76, respectively. Using various CH3CN−0.01 M KH2PO4 mixtures as eluents, the antiepileptic drugs were separated on all the glasses studied, but with different degrees of resolution. With an increase in the specific surface area, the k′ values of some antiepileptic drugs also increased.
    Type of Medium: Electronic Resource
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 39 (1994), S. 29-34 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Calcium modified silica ; Calcium adsorption isotherms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The modification of silica surfaces by calcium ions has been studied by high-performance liquid chromatography. After treatment at pH 7.0 and 9.0 with calcium hydroxide, the modified silicas were characterised by physical and chemical analysis. From measurements by atomic absorption, the amount of calcium adsorbed was 650 ppm on silica modified at pH 7.0, and 4800 ppm on silica modified at pH 9.0. The amount of calcium on the modified silica was 0.574 groups nm−2 at pH 9.0 (original silica: mean pore diameter 176 Å, specific surface 279 m2 g−1, pore volume 1.23 ml g−1, mean particle size 9.8 μm). On the other hand, the amount of calcium in the original silica was 58 ppm. The separation factor, α for N-methylaniline and N,N-dimethylaniline was 5.2 on silica modified at pH 9.0, but could not be measured on silica modified at pH 7.0 and the original silica, using iso-propyl alcohol—n-hexane (0.5∶99.5) eluent.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Polycyclic aromatic hydrocarbons ; Column liquid chromatography ; Polyphenyl bonded phases ; Retention and carbon content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the retention of PAHs having various molecular sizes and the carbon contents (%) of bonded stationary phases with various types of ligands were investigated. The examined stationary phases were phenyl, diphenyl, triphenyl and benzyl-bonded silicas. The data indicated that sometimes it is not true that the retention of any solute relates linearly to the carbon content of the stationary phase. As the result, it is suggested that the pore size distribution of the silica support, the bulkiness of the ligand bonded to the silica and the molecular size of solute should also be considered before any precise statement can be made.
    Type of Medium: Electronic Resource
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  • 7
    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.
    Type of Medium: Electronic Resource
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