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  • Column liquid chromatography  (361)
  • Springer  (361)
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  • 1
    Electronic Resource
    Electronic Resource
    Determination of carbendazime in lettuce samples by SFE-HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 395-399 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; Column liquid chromatography ; Carbendazime analysis ; Vegetable samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An SFE-HPLC method for the determination of carbendazime in lettuce leaves is described. The method involves a prior lyophilization of the sample and subsequent extraction with supercritical carbon dioxide containing methanol. The extraction conditions are as follows: amount of lyophilized sample, 1 g; CO2 density, 0.75 g/ml; temperature, 50 °C; flow-rate, 1.8 ml/min; dynamic extraction time, 25 min. Carbendazime is determined with an octadecylsilane column, an acetonitrile/water 30∶70 mobile phase and fluorescence detection at 285/317 nm. Carbendazime recoveries from spiked samples were all close to 100%. A comparison with the results from a conventional method for the determination of carbendazime reveals the new method to be more rapid, simple and reproducible for samples with low concentrations of analyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269786
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of tacrolimus (FK 506) in whole blood using liquid chromatography and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 490-496 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatization ; Dansylhydrazine ; Fluorescence detection ; Tacrolimus (FK 506) in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective liquid chromatographic method, using precolumn derivatization with dansylhydrazine followed by fluorescence detection, has been developed for the determination of tacrolimus (FK 506) in whole blood. After haemolysis, whole blood samples are extracted with diethyl ether and derivatized. After on-line removal of excess dansylhydrazine on a C18 precolumn, the derivative is loaded on to a C18 clean-up column, and a heart cut is subsequently transferred to a graphitized carbon column, where the final separation takes place. The method requires 1 ml of sample and has a limit of quantitation of 3 ng/ml. At the 15 ng/ml level the precision isca 10%, and the response is linear from the limit of quantitation toca 200 ng/ml of FK 506 in whole blood. The capacity of the method is 50 samples/day and about 1000 1-ml samples can be analyzed without changing either clean-up or separation column. Finally, the applicability of the method for therapeutic drug monitoring is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278767
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Molecular shape recognition capability of liquid-crystal bonded phases in reversed-phase high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 295-303 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystal phases ; Molecular shape recognition ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic retention behaviour of two liquidcrystal bonded phases have been evaluated using polycyclic aromatic hydrocarbons (PAHs) as the probe samples in reversed-phase high performance liquid chromatography (RP-HPLC). The results clearly indicate that these phases have better planarity and shape recognition capabilities than commercially-avaialble polymeric octadecylsilica (ODS) phases whose strong planarity and shape selectivities were found earlier. It can also be concluded from the chromatographic observations that the shape recognition capability of these phases is dependent on both mobile phase composition and column temperature, but that the effect of mobile phase and temperature on the shape selectivity work independently. The retention behaviour can be explained by changes in the phase structure with changes of eluent composition and temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269771
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of ethinylestradiol and gestodene in oral contraceptives by micellar electrokinetic chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 65-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar electrokinetic chromatography (MEKC) ; Oral contraceptives ; Ethinylestradiol ; Gestodene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A micellar electrokinetic chromatographic method is presented which permits quantification of ethinylestradiol and gestodene in pharmaceutical products. Separation was carried out at 25°C and 25 KV, using a 20 mM borate buffer (pH 9.2), 15 mM sodium dodecylsulfate in 30% acetonitrile-water (v/v). Under these conditions analyses were carried out in 7 min. Four different oral contraceptives were analysed and the results compared favourably with those of a reference liquid chromatographic method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467189
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  • 6
    Electronic Resource
    Electronic Resource
    Simultaneous separation of inorganic anions and cations using binary eluent by ion chromatography with indirect photometric detection (1996)
    Springer
    Chromatographia 43 (1996), S. 473-476 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Indirect detection ; Binary eluent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Inorganic cations and anions were separated simultaneously using sodium sulfosalicylic-EDTA binary eluent on a strong basic anion-exchange column. The effects of eluent pH, concentration and complexing effect of EDTA on retention behaviour of the ions were studied. The results showed that the larger the cation, the longer the retention time — except for Ca2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292996
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of triethylamine in the mobile phase on the retention properties of conventional polymeric and horizontally polymerized octadecylsilica in RPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 635-642 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Interaction of mobile and stationary phases ; Linear solvation energy relationships ; Triethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of triethylamine (TEA) in the mobile phase on the RPLC retention behavior of small organic solutes has been studied on a conventional polymeric octadecylsilica (ODS) and on a horizontally polymerized ODS. Retention factors for a set of solutes were measured on the two phases with methanol-water mobile phases containing triethylamine at different concentrations and analyzed by use of linear solvation energy relationships (LSER). Variation of the resulting LSER coefficients—v (hydrophobicity),r (polarizability),s (dipolarity),b (hydrogen-bond (HB) donating acidity), anda (HB accepting strength)—were examined to see how TEA affects the intermolecular interaction properties of the mobile and stationary phases and hence the retention of the solutes. Addition of TEA to the mobile phase changes the interaction properties of both conventionally polymerized and horizontally polymerized ODS; the effect is greater for the conventional phase. The HB donating acidity (b) of conventional polymeric ODS is significantly reduced by addition of TEA. For the mobile phases studied the magnitudes of theb andv coefficients for the horizontally polymerized ODS phase are greater than for the conventional phase. The different interaction properties of the two polymeric phases arise mainly as a result of differential adsorption of TEA, because of the very different amounts of surface silanol groups present on the two phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466905
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Retention behavior of some monobasic penicillins and their quaternary ammonium ion pairs in reversed-phase high-performance liquid chromatography (1991)
    Springer
    Chromatographia 32 (1991), S. 436-440 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Quaternary ammonium ion pairs ; Penicillins ; Retention behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of some monobasic penicillins (penicillin G, penicillin V, oxacillin, cloxacillin and dicloxacillin) and their quaternary alkylammonium ion pairs has been studied in a reversed-phase high-performance liquid chromatographic system using Partisil 5 μm ODS-3 asstationary phase and mixtures of acetonitrile and aqueous phosphate buffers as mobile phases. The influence of pH, pairing-ion chain length and concentration, and column temperature on retention has been investigated and the observed behavior of the compounds during the chromatographic process has been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02327974
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  • 10
    Electronic Resource
    Electronic Resource
    Simultaneous quantitative measurement of a new platelet activating factor antagonist (BN 50730) and its two main metabolites in human plasma and urine by LC-MS (1994)
    Springer
    Chromatographia 39 (1994), S. 228-238 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; LC/MS coupling ; Particle Beam interface ; Plasma and urine samples ; BN50730 and its metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive assay has been developed for the quantitative measurement of a new platelet activating factor antagonist (BN50730), and its two main metabolites (BN50727 and BN50922), at the picomole level in human plasma and urine. The three compounds of interest and the internal standard (BN50765) were measured by combined LC-negative chemical ionization MS. A simple solid-liquid extraction procedure was used to isolate the parent drug and the two metabolites. The MS was tuned to monitor the intense ionm/z 333 generated in the ion source by a dissociative capture process. The assay was on 1 ml plasma or 0.1 ml urine and the quantitation limit was calculated as 1 ng·ml−1. The very low relative standard deviations and mean percentages of error calculated for within-day or between-day repeatability assays demonstrate the ruggedness of the technique for routine determination in biological fluids. Some preliminary results on the pharmacokinetics of the parent drug and its two main metabolites illustrate the applicability of this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274505
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