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  • Articles  (62)
  • Column liquid chromatography  (62)
  • Springer  (62)
  • American Geophysical Union
  • 2020-2023
  • 2020-2020
  • 1995-1999  (62)
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  • Articles  (62)
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  • 1
    Electronic Resource
    Electronic Resource
    Study on the relationship between retention behavior and molecular structure parameters of substituted benzene derivatives in RPLC (1996)
    Springer
    Chromatographia 42 (1996), S. 43-48 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Substituted benzenes ; Solubility parameter ; Substituent constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A quantitative structure-retention model derived from the concept of hydrophobic substituent constant (π) and the total solubility parameter (δT) has been established. It has been used to predict successfully the retention behavior of a number of solutes on various columns in several different eluents. The experimental results indicate that the model can be employed for the prediction of retention of substituted benzenes in a large volume fraction range of mobile phase. In addition, the physical meaning of the sign and the influence of the coefficients of the model on the retention process had been discussed together with the dependence of these coefficients on the composition of mobile phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271054
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of 8[(3S)-3-amino-1-pyrrolidinyl]-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-3-carboxylic acid hydrochloride and related substances by high performance liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 141-147 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluoroquinolones ; Quinolizines ; Impurity Profile ; Abbott compound 086719.1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The purity of the investigational antibacterial Abbott-086719.1 (I) which is 8[(3S)-3-amino-1-pyrrolidinyl]-1-cyclopropyl-7-fluoro-9-methyl-4-oxo-4H-quinolizine-3-carboxylic acid hydrochloride is determined using gradient elution HPLC. The chromatographic separation was optimized and the chromatographic parameters critical to separation are discussed in detail. Most acceptable separations were achieved using an Alltima C18 column (5 μm) measuring 4.6 mm I.D.×15 cm with 0.01M–0.03M citrate eluents which were modified with acetonitrile or with mixtures of acetonitrile and methanol. Related substances in I were determinable to 0.05%. Repeatability (RSD values) for determining related substances at levels of 0.50 to 0.06% ranged from ±1.9 to ±10%. Determinations of I in 5% dextrose in water and in hydroxypropyl methylcellulose were made using the same column and a simple isocratic system. The determination of I was stability indicating with precision (RSD values) of ±0.5% to ±2.0% and good agreement with theory for formulations containing I at 1.0 to 95 mg/mL concentrations. Recoveries of I from the vehicles were quantitative and linearity of the detector response of I was demonstrated to at least 0.10 mg/mL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267945
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  • 3
    Electronic Resource
    Electronic Resource
    A statistical study of the correlation between k′ or log k′ and log Pow for a group of benzene and naphthalene derivatives in micellar liquid chromatography using a C-18 column (1995)
    Springer
    Chromatographia 40 (1995), S. 185-192 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid phases ; Octanol-water partition coefficient ; Benzene and naphthalene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the logarithm of the capacity factor (log k′) for fifteen benzene and naphthalene derivatives in micellar liquid chromatography with forty nine different mobile phases generally correlates better with the logarithm of the octanol-water partition coefficient (log Pow) than the capacity factor (k′). Optimum conditions are established to obtain the best linear correlations of log k′-log Pow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272169
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  • 4
    Electronic Resource
    Electronic Resource
    High performance liquid chromatographic determination of methyl ethyl ketone in urine as its 3-methyl-2-benzothiazolinone hydrazone derivative (1995)
    Springer
    Chromatographia 40 (1995), S. 336-340 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methyl ethyl ketone in urine ; Derivatization ; 3-Methyl-2-benzothiazolinone hydrazone ; Comparison with GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A HPLC method for the determination of methyl ethyl ketone (MEK) in urine after derivatization with 3-methyl-2-benzothiazolinone hydrazone is proposed. The calibration curve for the ketone was linear, ranging between 0.23–10 mg/L, with a detection limit of 0.025 mg/L. The results were compared to those obtained by GC-MS, coupled to the headspace technique. MEK derivatization and the derivative purification processes were verified with respect to the main variables such as reaction temperature, reagent concentration, probable interferences and enrichment phase. The method is simple and reliable and shows a good sensitivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290366
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  • 5
    Electronic Resource
    Electronic Resource
    Retention parameters of some isomeric 2-benzoylbenzoic acids in reversed-phase ion-pair high performance thin-layer and column chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 453-457 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Reversed phase ; 2-benzoylbenzoic acids ; Anionic and cationic counter ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by Δlog k′ and ΔRM values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269912
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of D- and L-amino acids in biological samples by two-dimensional column liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 6-14 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Two-dimensional separation ; D- and L-amino acids ; Enantioseperation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 μl heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274188
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  • 7
    Electronic Resource
    Electronic Resource
    Retention of fullerenes by octadecyl silica. Correlation with NMR spectra at low temperatures (1995)
    Springer
    Chromatographia 40 (1995), S. 507-512 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; Retention vs NMR spectra ; C18 phases ; Low temperature separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The temperature effect on the retention of fullerenes in the range 80°C to −70°C in liquid chromatography (LC) has been examined using octadecylsilica stationary phases (ODS). It has been found that the maximum retention temperature lies around −10°C with a highly carbon loaded ODS phase. Solid state CPMAS NMR measurements on the stationary phases indicated that the relaxation time at the 30 ppm methylene signal changes with the temperature and has a minimum relaxation time at the temperature which closely matches the maximum retention temperature observed in chromatography. The interpretation of both NMR spectroscopic and LC chromatographic data are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290260
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  • 8
    Electronic Resource
    Electronic Resource
    Modelling and prediction of retention in high-performance liquid chromatography by using neural networks (1995)
    Springer
    Chromatographia 41 (1995), S. 435-444 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Neural networks ; Retention modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multi-layer feed-forward neural networks trained with an error back-propagation algorithm have been used to model retention behaviour of liquid chromatography as a function of the composition of the mobile phases. Conventional hydro-organic and micellar mobile phases were considered. Accurate retention modelling and prediction have been achieved using mobile phases defined by two, three and four parameters. With micellar mobile phases, the parameters involved included the concentrations of surfactant and organic modifier, pH and temperature. It is shown that neural networks provide a competitive tool to model varied inherent nonlinear relationships of retention behaviour with respect to the mobile phase parameters. The soft models defined by the weights of the networks are capable of accommodating all types of linear and nonlinear relationships, neural networks being specially useful when the relationships between retention behaviour and the mobile phase parameters are unknown. However, to train neural networks more experimental points than with hard-modelling methods are required, hence the use of the networks is recommended only for those cases where adequate theoretical or empirical models do not exist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02318619
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  • 9
    Electronic Resource
    Electronic Resource
    Separation of saponins and determination of quinovic acid 3-O-α-L-rhamnopyranoside fromNauclea diderrichii (de Wild) Merr. Bark by high performance liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 581-584 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nauclea diderrichii (de Wild) Merr ; Saponins ; Alkaloid glycoside ; Chrysanthelline A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase HPLC determination of 11 saponins and an alkaloid glycoside inNauclea diderrichii bark is described. Quantitative analysis of quinovic acid 3-O-α-L-rhamnopyranoside which is one of the main saponins was determined, using Chrysanthelline A as internal standard. The complete separation was achieved in 47 minutes. The method of quantification was validated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269723
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  • 10
    Electronic Resource
    Electronic Resource
    Normal and reversed-phase HPLC for more complete evaluation of tocopherols, retinols, carotenes and sterols in dairy products (1996)
    Springer
    Chromatographia 43 (1996), S. 89-93 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sterols, tocopherols, retinols and carotenes ; Dairy products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have previously described a normal-phase HPLC method for the simultaneous determination of α, β, γ and δ tocopherol, thecis andtrans isomers of retinol, and total carotenes in different Italian cheeses and milk. In this paper we describe a reversed-phase HPLC method using solely methanol as the mobile phase for the determination of α-tocopherol, β-+γ-tocopherols, total retinols, cholesterol, β-sitosterol, campesterol and stigmasterol, and α- and β-carotene. The method developed has been applied to some new dairy products such as natural Quark, with olive, basil or banana and to processed cheese with tomato and the results have been compared with the corresponding results obtained by the normal-phase method. The conclusion is that more complete evaluation of the tocopherol, retinol, carotene and sterol content of dairy products, especially when vegetables and fruits are present, is necessary and can be obtained using both the normal- and reversed-phase HPLC methodologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272829
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