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  • Column liquid chromatography  (92)
  • Springer  (92)
  • Nature Publishing Group
  • 1990-1994  (92)
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  • Springer  (92)
  • Nature Publishing Group
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Quantitative structure chromatography relationships in reversed-phase high performance liquid chromatography: Prediction of retention behaviour using theoretically derived molecular properties (1993)
    Springer
    Chromatographia 37 (1993), S. 241-249 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pattern recognition ; Principal components ; Multiple linear regressions ; M.O. properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of theoretically calculated molecular properties as predictors for retention in reversed-phase HPLC has been explored. HPLC retention times have been measured for a series of 47 substituted aromatic molecules in three solvent mixtures and steric and electronic properties of these compounds have been derived using semi-empirical molecular orbital and empirical theoretical methods. A subset of the experimental data (a training set) was used to derive property-retention time relationships and the remaining data were then used to test the predictive capability of the methods. Good retention time prediction was possible using derived regression equations for individual solvents and after including solvent parameters it was possible to predict retention for all solvents using a single equation. This method showed that the most useful properties were calculated log P and the calculated dipole moment of the solutes, and the calculated solvent polarisability. In addition, 90% of the data were used to train an artificial neural network and the remaining 10% of the data used to test the network; excellent prediction was obtained, the neural network approach being as successful as the regression analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278628
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  • 2
    Electronic Resource
    Electronic Resource
    The use of chiral interaction reagents in the separation of D(−)-and L(+)-ascorbic acid by ion interaction reversed-phase HPLC (1990)
    Springer
    Chromatographia 30 (1990), S. 311-317 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral interaction reagents ; Vitamin C ; D(−)-and L(+)-ascorbic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC reversed-phase ion interaction reagent method is presented, which makes use of chiral compounds as the interaction reagents. By employing the optical isomeric forms of malic, tartaric and mandelic acids as the interaction reagents, a good separation of D(−) and L(+) ascorbic acid has been achieved. The method has also been applied to the identification of vitamin C in some medical formulations. The separation of te enantiomeric forms of DL malic acid has been attempted and a shor discussion is presented about the elution sequence in chromatographic separation of D- and L-enantiomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319714
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  • 3
    Electronic Resource
    Electronic Resource
    Separation of food-related biogenic amines by ion-interaction reversed-phase high performance liquid chromatography. Tyramine, histamine, 2-phenylethylamine, tryptamine and precursor aminoacids. Application to red wine (1991)
    Springer
    Chromatographia 31 (1991), S. 381-386 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biogenic amines ; Wine ; Food-related biogenic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods for the separation of food-related biogenic amines (histamine, tyramine, 2-phenylethylamine and tryptamine) have been developed based on ion-interaction reversed-phase liquid chromatography. Two different interaction reagents have been comparatively used, namely octylamine ortho-phosphate (at wave-lengths of 230, 254 and 280 nm) and octylamine salicylate (at a wavelength of 254 nm). The different elution sequence orders shown by the investigated amines for the two reagents are discussed and compared. The detection limits obtained were 20 ppb for tryptamine (λ =280 nm), 500 ppb for 2-phenylethylamine (λ=254 nm), 400 ppb for tyramine (λ=230 or 280 nm) and 900 ppb for histamine (λ=230 nm). The method was applied to the analysis of a five years old Italian red wine, in which 2-phenylethylamine (at a concentration of 72±3 ppm) and tryptamine (at a concentration of 4.0±0.3 ppm) were found to be present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262196
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  • 4
    Electronic Resource
    Electronic Resource
    HPLC in the investigation of taxonomic problems. Classification of poplar genotypes (1990)
    Springer
    Chromatographia 29 (1990), S. 355-362 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoids ; Poplar tree taxonomy ; Fingerprinting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The RP-HPLC technique has been applied to the analysis of the flavonoid content of leaf extracts from various genotypes ofPopulus nigra andPopulus deltoides and from several of their hybrids. Two elution procedures different either as regards gradient program or the type of organic modifier used were checked to optimize the reliability of the results obtained. Before making any identification, the chromatographic profiles proved so typical of each species as to allow of their use as fingerprints in this type of taxonomic problem. Individual identifications were carried out by spiking real samples with known amounts of standard substances. The presence of flavonoid compounds previously identified was confirmed and a few new identifications were proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261303
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of sulbutiamine and its disulfide derivatives in human plasma by HPLC using on-line post-column reactors and fluorimetric detection (1993)
    Springer
    Chromatographia 36 (1993), S. 167-173 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid-phase extraction ; On-line post-column reaction ; Sulbutiamine ; Thiamine disulfide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new direct HPLC procedure for the simultaneous determination of sulbutiamine (Arcalion) and other thiamine disulfides in human plasma has been developed. The method involves an automated solidphase extraction on octadecylsilyl (C18) cartridges and chromatographic separation of the compounds on an RP Select B column with gradient elution using methanol and phosphate buffer. Detection was by fluorescence of the resulting thiochromes obtained from two on-line post-column reactors. Optimization of post-column reaction parameters has been achieved. This method has been proved to be highly selective for the determination of the thiamine disulfide derivatives and quantitation limits of 5 ng·ml−1 were obtained for each compound in human plasma. Linearity was in the range 5–200 ng·ml−1. Precision and accuracy were also demonstrated by within-day and between-day assays, and showed the good reliability of the method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263856
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  • 6
    Electronic Resource
    Electronic Resource
    Simultaneous assay of platelet and plasma catecholamines by HPLC with coulometric detection (1993)
    Springer
    Chromatographia 36 (1993), S. 164-166 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Platelet ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Platelets and monoaminergic neurons share many morphological, biochemical, and pharmacological properties. In addition to its similarities to serotonergic nerve endings, the platelet has also been considered a good model for the study of the noradrenergic function, since it can selectively take up, store, and release norepinephrine (NE). In this study platelet and plasma levels of free catecholamines (CA) in 20 healthy subjects have been determined by HPLC with a reversed phase (C18) ionpairing system equipped with a coulometric detector. Direct correlation was observed between platelet and plasma levels of NE. A positive correlation was also found between the age of the sujects and both platelet and plasma NE levels. While showing that the peripheral noradrenergic hyperactivity of the elderly is also reflected in platelet NE content, this study also demonstrates that simultaneous assay of platelet and plasma CAs can be a useful tool for an integrated and more complete evaluation of sympathetic nervous system activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263855
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  • 7
    Electronic Resource
    Electronic Resource
    On-line monitoring of fermentation processes by ultrafiltration and column liquid chromatography (1992)
    Springer
    Chromatographia 33 (1992), S. 525-532 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ultrafiltration ; Fermentation monitoring ; Sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated on-line monitoring system for low-molecular-weight compounds (e.g. sugars) during fermentation processes is described. The applicability of cross-flow ultrafiltration, coupled on-line with high-performance liquid chromatography, is evaluated. Various detection modes for the determination of the test compounds lactose, glucose and fructose) in a complex fermentation broth are compared. In addition, the influence of some system parameters on the performance of several ultrafiltration modules for the removal of cellular and macromolecular broth constituents is investigated. A method for the fully automated determination of sugars during anE. coli batch culture in a brain-heart infusion medium is presented. With the present system five analyses can be performed every hour, using only 35μl of sample, without significant deterioration of the ultrafiltration process. Contamination by external micro-organisms was not observed and good correlation with an off-line method was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262243
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  • 8
    Electronic Resource
    Electronic Resource
    Preparation and evaluation of cross-linked polyacrylate stationary phases for open tubular liquid chromatography (1993)
    Springer
    Chromatographia 35 (1993), S. 597-606 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Open tubular columns ; Cross-linked polyacrylate stationary phase ; Photopolymerization ; Antracene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyacrylate films containing a lauryl moiety were fabricated on about 12 μm I.D. fused silica capillaries by in-situ photopolymerization of acrylates. Relatively thick films up to 1 μm were obtained by the technique. The films were tested as retentive layers for reversed phase open tubular liquid chromatography (OTLC). Due to the presence of the incorporated lauryl moiety in the layer considerable retention could be achieved for polar compounds with aqueous mobile phases. The efficiency of the prepared columns approximates to the theoretical value. The polyacrylate films appear to be extremely stable even under strong basic conditions. The films swell considerably in the presence of nonpolar solvents resulting in more favourable retention and a significant improvement of the chromatographic performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267923
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  • 9
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic separation of fullerene mixtures using a novel stationary phase (1993)
    Springer
    Chromatographia 35 (1993), S. 631-636 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; FullereneSep® ; Separation factor ; HPLC-particle beam mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic separation of fullerene mixtures in the range C60 to C100 can be achieved using a novel stationary phase which rivals the performance of the more expensive ‘Pirkle-type’ columns currently employed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267928
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  • 10
    Electronic Resource
    Electronic Resource
    Chromatography in pore networks II — The role of structure and adsorption in the band broadening (1991)
    Springer
    Chromatographia 32 (1991), S. 345-349 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column packings ; Pore size distribution ; Diffusion and adsorption ; Band broadening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The complex intraparticle structure typical of chromatographic column packings has been analyzed by use of an equivalent network model which emphasizes pore size distribution and connectivity. Special attention is given as to the way in which diffusion and adsorption interact and display modified peak spreading characteristics according to the morphology of the pore space. This study reveals a very significant increase in the column band broadening over that expected from physical adsorption which can arise from particular distributions of pore sizes. This has implications for designing packings which take advantage of the separating power due to adsorption but do not compromise the resolution of the chromatographic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321432
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