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  • Column liquid chromatography  (37)
  • Springer  (37)
  • 1995-1999  (37)
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  • Chemistry and Pharmacology  (37)
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  • Articles  (37)
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  • Springer  (37)
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  • 1995-1999  (37)
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  • Chemistry and Pharmacology  (37)
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  • 1
    Electronic Resource
    Electronic Resource
    Optimisation of chiral separation of omeprazole and one of its metabolites on immobilized α1-acid glycoprotein using chemometricsglycoprotein using chemometrics (1997)
    Springer
    Chromatographia 44 (1997), S. 10-18 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Experimental design ; Direct chiral resolution ; Omeprazole ; Hydroxy-omeprazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A strategy for the optimisation of direct chiral separation of omeprazole and a metabolite, hydroxi-omeprazole, in reversed phase liquid chromatography is described. A factorial design was used, where mobile phase pH, concentration of a mobile phase modifier, ionic strength and column temperature were tested as the variables and enantioselective retention, column efficiency and asymmetry factor as the responses. The experimental results were evaluated with multivariate analyses, which demonstrated that the column temperature and content of mobile phase acetonitrile were by far the most important variables. The enantiomers of omeprazole and one of its metabolites were baseline resolved within 15 minutes. The optimised chromatographic system was used for a separation of the enantiomers of omeprazole and its main metabolite in a patient plasma sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466509
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  • 2
    Electronic Resource
    Electronic Resource
    Chemiluminescence determination of tiopronin and its metabolite 2-mercaptopropionic acid in human urine by HPLC coupled with flow injection (1997)
    Springer
    Chromatographia 44 (1997), S. 31-36 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemiluminescence detection ; Tiopronin ; Thiols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In previous pharmacokinetic studies tiopronin, a drug used for effective treatment of cystinuria and rheumatoid arthritis, and its metabolite 2-mercaptopropionic acid were analysed by conventional liquid chromatography with pre- and post-column derivatization and UV detection. Now a novel HPLC-coupled chemiluminescence-flow-injection analysis (CL-FIA) method has been developed for the determination of tiopronin and 2-mercaptopropionic acid in urine. The method is based on chemiluminescence from a Ce(IV) oxidation system sensitized by quinine, as proposed earlier by this group, and flow-injection analysis. The method, which has the advantages of high sensitivity and selectivity, simple sample treatment and prompt production of results, has also been preliminarily adapted for pharmacokinetic study of tiopronin in urine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466512
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  • 3
    Electronic Resource
    Electronic Resource
    HPLC analysis of fat-soluble vitamins on standard and narrow bore columns with UV, electrochemical and particle beam MS detection (1997)
    Springer
    Chromatographia 44 (1997), S. 605-612 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV and electrochemical detection ; Particle beam-mass spectrometry ; Fat-souble vitamin ; Standard-bore and narrow-bore columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The application of different detection techniques; UV, electrochemical (ED) and particle beam-mass spectrometry (PB-MS) for the high-performance liquid chromatography analysis of fat-soluble vitamins were studied. Separation of all compounds examined was performed using both C8 standard-bore and narrow-bore columns for UV and MS detection, whereas in the case of HPLC-ED, a C8 standard-bore column only was used. Detector responses were studied in terms of linear range, detection limit and precision. The HPLC methods with UV, PB-MS and electrochemical detection were applied to the assay of vitamins A and E in an infantformula, powdered-milk sample. Recovery studies showed good results both for vitamins A and E, within-run precision being 2–4% for LC-UV and LC-ED techniques. In addition, excellent aggrement between the results obtained with the detection systems explored was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466663
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of cortisol in guinea pig urine by high performance thin-layer chromatography, high performance liquid chromatography, and thin-layer chromatography/radioimmunoassay (1997)
    Springer
    Chromatographia 44 (1997), S. 50-54 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Column liquid chromatography ; Radioimmunoassay ; Cortisol ; Guinea pig ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to collect urinary samples from unrestrained guinea pigs, animals were kept in their familiar home cages with wood shavings for bedding. Cortisol was removed from shavings by a simple washing step, and an attempt was made to measure its concentrations by high performance thin-layer chromatography (HPTLC), high performance liquid chromatography (HPLC), or thin layer chromatography/radioimmunoassay (TLC-RIA). After intramuscular administration of 25 mg cortisol, cortisol excretion increased from about 20–30 μg/day to 400–500 μg/day (HPTLC: 531 μg/day, HPLC: 493 μg/day; TLC-RIA: 394 μg/day). Similarly, the treatment of the animals with 20 IU ACTH resulted in an augmented cortisol excretion, with mean values of 294 μg/day (HPTLC), 256 μg/day (HPLC) and 143 μg/day (TLC-RIA), respectively. The present study shows, for the first time, that cortisol excretion in unrestrained laboratory animals can be determined. Whilst the cortisol values measured by HPTLC and HPLC agree, the amounts measured by TLC-RIA were significantly lower. These differences are probably due to the presence of substances in urine or shavings which interfere with the radioimmunological determination. Hence, cortisol should be determined either by HPTLC or HPLC. Beside having a desirable specificity, these methods are more suited than TLC/RIA for steroid analysis since they confer the possibility of measuring additional steroids (e.g. precursors and/or metabolites of cortisol) in a single urine extract. This is especially the case for the HPTLC method since substances can be transformed into fluorescent derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466515
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  • 5
    Electronic Resource
    Electronic Resource
    Development of a universal Raman detector for microchromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 257-262 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microchromatography ; Raman spectroscopy ; Deuterated solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detector for microchromatography in which Raman spectroscopy is used to identify the eluted species has been developed. The detector is designed to be applicable to a wide range of compounds without requiring the presence of a chromophore. Its use is illustrated in the analysis of nitro compounds on a 250 μm i.d. column. Raman spectra of each of the compounds could be identified as they passed the detector. The advatages of the use of fully deuterated solvents are demonstrated by the analysis of nitrobenzenes in methanol/water mobile phases. The detection limit for nitrobenzene using the Raman line at 1342 cm−1 was 75ng.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466391
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  • 6
    Electronic Resource
    Electronic Resource
    Development and validation of a stability-indicating HPLC method for the determination of degradation products in dipyridamole injection (1997)
    Springer
    Chromatographia 44 (1997), S. 247-252 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dipyridamole injection ; Stability studies ; Degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The development and subsequent validation of an isocratic high-performance liquid chromatographic (HPLC) procedure employing ultraviolet (UV) detection for the determination of degradation products in Dipyridamole Injection is reported. The development of this assay involved the evaluation of several factors including buffer type, ionic strength, pH, organic composition, and column type. The described method is simple, reproducible, accurate, and selective. The precision, relative standard deviation (RSD), amongst five sample preparations for total degradation products was not more than (NMT) 10.2 %, while the individual degradation products were NMT 12.1%. Intermediate precision, as determined from fifteen sample preparations, generated by two Analysts on different HPLC systems over three days, exhibited an RSD for total and individual degradation products of 8.2 % and NMT 27.5 %, respectively. The mean absolute recovery of dipyridamole using the described method is 102.1±1. 9%, (mean±SD, n=12) over the concentration range of 0.03 % to 5.0 % of its label claim of 5 mg mL−1. The limit of detection and limit of quantitation were 0.1 and 0.3 μg mL−1, respectively. The linearity of the peak response was verified with respect to dipyridamole concentration over a range of 0.3 and 50 μg mL−1 (0.03 % to 5.0 % label claim). The Standard and Assay Preparations are stable for up to 48 hours at room temperature. The selectivity was evaluated by subjecting the finished product (Dipyridamole Injection) to thermal, acidic, basic, oxidative and fluorescent radiation stress conditions. No interference in the analysis of degradation products was observed, showing the method is stability-indicating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466389
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  • 7
    Electronic Resource
    Electronic Resource
    A weak cation-exchange phase for the separation of biogenic amines by open tubular liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 295-302 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Open tubular columns ; Weak cation-exchange stationary phase ; Biogenic amines ; LIF detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation and performance of a weak cation-exchange stationary phase for Open Tubular Liquid Chromatography (OT-LC) was investigated. The stationary phase was prepared in 5.4 μm I.D. fused silica capillaries byin situ photopolymerization of a mixture of silicon acrylate and acrylic acid. The influence of pH, counter ion concentration and organic modifier concentration of the mobile phase on the retention was studied with catecholamines as test solutes using LIF detection. Other biological amines like amino acids, small peptides and nucleic acid derivatives could be separated on this stationary phase as well. The kinetic performance of the stationary phase was studied with several cations and neutral solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466398
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  • 8
    Electronic Resource
    Electronic Resource
    Quantitative analysis of mebeverine in dosage forms by HPLC (1997)
    Springer
    Chromatographia 44 (1997), S. 427-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mebeverine in dosage forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and rapid, high performance liquid chromatographic (HPLC) procedure for determination of mebeverine in dosage forms (tablet and liquid) is described. Reversed-Phase chromatography was carried out using a mobile phase containing 0.05 M ammonium acetate buffer and acetonitrile, [(45%, v/v) pH 5.2] with UV-detection (263 nm). Replicate regression analyses of three standard plots in the concentration range of 0.5–10 mcg mL−1 obtained on three different days gave a correlation coefficient 〉0.9995 and the coefficient of variation of the slopes 〈2.2%. The assay was precise within day and between days as indicated by ANOVA test. The recoveries from 10 replicate tablets of two commercial mebeverine brands and liquid were in order 99.3, 100.5 and 100.1% of the label amount and their coefficient of variations were 1.41, 0.89 and 0.69%, respectively. The limit of quantitation of mebeverine was 5 ng mL−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466322
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis of new stable aliphatic isothiocyanate-based chiral derivatizing agent and application to indirect separation of chiral amino and thiol compounds (1997)
    Springer
    Chromatographia 44 (1997), S. 465-472 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Indirect separation ; Chiral derivatization ; Stable CDA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new chiral derivatizing agent (CDA) (1S, 2S) N-[(2-isothiocyanato)-cyclohexyl)-pivalinoyl amide ((S,S)-PDITC) is described. The CDA is available from 1,2-diamino cyclohexane (DACH) via a straightforward synthesis in both the (R,R) and (S,S)-configuration and can serve as a highly selective, stable reagent for the indirect resolution of chiral primary and secondary amines, amino acids and thiol compounds. The resulting diastereomeric thioureas and dithiocarbamates can be separated by simple RP-HPLC as demonstrated with a number of pharmaceutically important examples of amines and amino alcohol-type drugs. The latter diastereomers are compared with the well-established GITC derivatized compounds. The separation factors (α) of the diastereomeric thioureas range between 1.03 and 2.08 and were usually higher than those of the GITC derivatives. The chemical stability of the PDITC derivatives is excellent due to the absence of hydrolyzable ester groups— considered an advantage compared to GITC derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466738
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of titania based stationary phases using the silanization/hydrosilation method (1997)
    Springer
    Chromatographia 44 (1997), S. 538-544 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl titania ; Hydride surface ; Hydrosilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The silanization/hydrosilation bonding method is tested on both a laboratory synthesized and commercial titania. The laboratory titania made by the sol-gel process shows evidence of residual organic material that is removed by an initial acid hydolysis followed by bonding of the hydride (triethoxysilane) under acidic conditions. DRIFT and solid state CP-MAS NMR studies are used to confirm the formation of the hydride layer on the titania and the success of the hydrosilation process for attaching an organic moiety (1-octadecene) to the surface. Chromatographic testing, primarily on the commercial titania based C-18 phase, indicates good reverse phase properties and few residual OH groups, either Ti−OH or Si−OH, as determined by the symmetrical peak shapes obtained for anilines and alkylphenylamines using mobile phases with no buffers or masking agents in the aqueous component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466748
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  • 11
    Electronic Resource
    Electronic Resource
    Application of micropellicular poly-styrene/divinylbenzene stationary phases for high-performance reversed-phase liquid chromatography electrospray-mass spectrometry of proteins and peptides (1997)
    Springer
    Chromatographia 44 (1997), S. 438-448 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrospray ionization mass spectrometry ; Micropellicular poly-styrene/divinylbenzene ; Peptides and proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Short columns packed with highly crosslinked 2.3 μm poly-styrene/divinylbenzene (PS/DVB) particles were used for rapid and efficient separation of proteins and peptides by reversed-phase high-performance liquid chromatography at elevated temperatures. Enhancement of the diffusivities of the sample components at elevated temperatures together with the short diffusion pathlength with the micropellicular polymeric stationary phases were responsible for high efficiency, high speed of analysis, and short column regeneration times. Underivatized PS/DVB beads as well as PS/DVB microspheres which have been modified with polyvinylalcohol or octadecyl chains on the surface were synthesized, employed, and compared to HY-TACH-C18, a commercially available micropellicular octadecyl-silica stationary phase, for the separation of proteins, octapeptides and tryptic protein digests. Highest performance was obtained with the silica- and PS/DVB-based octadecyl stationary phases, which exhibited similar column efficiencies but different selectivities for proteins and peptides. The minimum detectability at 214 nm and the maximum loading capacity for ribonuclease A using analytical 30×4.6 mm I.D. columns were 10 ng (0.6 pmol) and 1 μg, respectively. Finally, reversed-phase HPLC with a 60×2 mm I.D. narrow-bore column packed with micropellicular octadecyl PS/DVB was coupled successfully to electrospray mass spectrometry at a flow-rate of 0.15 mL min−1 and on-line full-scan mass spectra for molecular mass determination and identification of proteins in the lower picomol range were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466324
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  • 12
    Electronic Resource
    Electronic Resource
    Simultaneous determination of parathion and metabolites in serum by HPLC with column switching (1997)
    Springer
    Chromatographia 44 (1997), S. 473-476 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column-switching ; Parathion, and metabolites in serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new high-performance liquid chromatographic method with column-switching has been developed for the simultaneous determination of parathion and its metabolites such asp-nitrophenol and paraoxon in serum. Serum samples were injected onto a precolumn packed with LiChroprep RP-8 after simple dilution with 20% phosphoric acid. Polar plasma components were washed with 0.02 M phosphate buffer (pH 3.0). After valve switching, the concentrated compounds were eluted in back-flush mode and separated on a Ultracarb ODS 30 column with a gradient of acetonitrile −0.01 M phosphate buffer (pH 3.0) as mobile phase. The method showed excellent precision, accuracy and speed with detection limit of 0.1 μg mL−1. Total analysis time per sample was 〈40 min and coefficients of variation for intra-and inter-assay were 〈4.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466739
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  • 13
    Electronic Resource
    Electronic Resource
    Comparison of GC-MS and HPLC for overcoming matrix interferences in the analysis of PAHs in smoked food (1997)
    Springer
    Chromatographia 44 (1997), S. 497-504 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas chromatography-mass spectrometry ; Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Food analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several separation and detection methods for polycyclic aromatic hydrocarbons (PAHs) in smoked chicken by GC and HPLC were compared. With HPLC and a gradient solvent system, all 16 PAHs could be simultaneously separated and detected by fluorescence with seven settings of programmable wavelength (excitation/emission). The presence of impurities in smoked chicken could interfere with the subsequent identification and quantification of PAHs by HPLC. With GC and a temperature programming method, all 16 PAHs could be separated and the PAHs in the chicken sample could be detected with an ion-trap mass spectrometer even in the presence of fat-or PAH-like impurities. Nine PAHs were identified by the former method while fourteen PAHs were identified by the latter method. The retention times by HPLC were shorter than those by GC, also, the former had better separation for most PAHs than the latter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466743
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  • 14
    Electronic Resource
    Electronic Resource
    Computerized optimization of RP-HPLC separation with nonaqueous or partially aqueous mobile phases (1997)
    Springer
    Chromatographia 44 (1997), S. 529-537 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Computer optimization of separation ; Multisolvent mobile phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary “Osiris” optimization software was usedfor optimizing separations with nonaqueous or partially aqueous mobile phases, consisting of 2, 3 or 4 solvents. For nonaqueous eluents used in Nonaqueous Reversed Phase Liquid Chromatography (NARP-LC), classical transfer rules cannot be used to determine isoeluent mobile phase compositions that are generally the starting point of most of the optimization procedures. The ability of this software to determine isoeluent compositions under NARP conditions is demonstrated. This determination is performed by modeling the solute retention from different sets of two gradient runs, each set being carried out for each binary mobile phase studied. The application of retention models to nonaqueous mobile phases is discussed in terms of the accuracy of the predicted retention times. In addition, it is shown that these sets of gradient runs allow selection of the best composition space for the optimum composition search without requiring additional runs. It is demonstrated that such a selection procedure greatly reduces the number of preliminary experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466747
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  • 15
    Electronic Resource
    Electronic Resource
    Reversed phase behaviour of high molar mass polystyrenes in acetonitrile with halogenated methane solvent mixtures (1997)
    Springer
    Chromatographia 44 (1997), S. 421-426 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; RP chromatography ; Polystyrenes ; Mixed solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reversed phase behaviour of high molecular mass polystyrenes was investigated on a C18 bonded phase column using acetonitrile as the polar mobile phase component and dichloromethane, chloroform and carbon tetrachloride, as separate nonpolar components. Solvent solubility compositions, elution compositions and resolutions of the various molar mass polystyrenes were measured and compared for each of the three mobile phases. Anomalous behaviour of the polystyrenes was not observed in any of the three mobile phases and only minor differences in resolution were observed. By comparing these results with previously published work, it is suggested that any mobile phase component that is both nonpolar and a good solvent for the polymer can be combined with acetonitrile for effective separations of polystyrenes by mass and that it is the poor solvent component of the mobile phase that is responsible for the anomalous behaviour that is sometimes observed in this type of chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466321
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  • 16
    Electronic Resource
    Electronic Resource
    Resolution of the enantiomers of verapamil and gallopamil by chiral liquid chromatography-mass spectrometry (1997)
    Springer
    Chromatographia 44 (1997), S. 477-483 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Calcium channel antagonists ; On-line liquid chromatography-mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC-CSP method has been developed for the separation of enantiomers of verapamil and gallopamil using the improved version of the α1-acid glycoprotein, chiral stationary phase as selector with a volatile mobile phase. The results of the investigation provide the conditions which allow direct coupling to a mass spectrometer. In addition, the simultaneous enantioseparation of both the enantiomeric pairs of verapamil and gallopamil was achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466740
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  • 17
    Electronic Resource
    Electronic Resource
    Determination of sorbic acid in wines with a hydrogen sulfonated divinyl benzene-styrene copolymer HPLC column (1997)
    Springer
    Chromatographia 44 (1997), S. 645-648 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Wine ; Sorbic acid ; Styrene-DVB sorbents ; Detection limit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for the determination of sorbic acid in wines using a hydrogen sulfonated divinyl benzene-styrene copolymer (DVB-H) HPLC column and isocratic elution with 0.01N H2SO4:CH3CN (75:25). UV detection at 258 nm permits analysis by direct injection of white and red wines without significant interference between the peaks of sorbic acid and other sample components. The limit of detectability of the method is 0.01 mg L−1 with an average recovery of 99.6% and an average % RSD of 0.87. Analyses of 30 wine samples by the proposed method and the official EEC spectrophotometric method show that there is a good correlation between the results of the two methods, although the HPLC analyses are clearly more precise and accurate.
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    URL: http://dx.doi.org/10.1007/BF02466668
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  • 18
    Electronic Resource
    Electronic Resource
    Chromatographic classification of commercially available reverse-phase HPLC columns (1997)
    Springer
    Chromatographia 44 (1997), S. 151-161 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reverse-phase LC columns ; Chromatographic classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ever-increasing number of commercially available reversed phases with which the analyst is confronted can cause problems in column selection. These and the non-standard test procedures used by the column manufacturers and packing companies cause further confusion. In order to independently compare and contrast a range of well established C18 stationary phases, we have performed a modified column characterization approach, based on Tanaka's methodology, on thirty commonly used phases in our laboratory. These results have been evaluated and presented in various formats as Principal Component Analysis, Cluster Analysis, Tabular Format and Radar Plots in order to assist in observing similarities and differences between phases. The results indicate that, while no two phases are exactly the same (with the exception of “me-to” clones), it is possible to characterize phases into different classes based on their chromatographic performance against selected test probes. The paper illustrates the similarities and differences between these phases. The column characterization described in the paper can form the basis of a rational column selection protocol by either careful matching of the appropriate column characteristics to the analyte's physico-chemical properties or by a systematic evaluation of columns from our various categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466449
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  • 19
    Electronic Resource
    Electronic Resource
    Influence of temperature and mobile phase composition on retention properties of oligomeric bonded phases in reversed-phase liquid chromatography (RPLC) (1997)
    Springer
    Chromatographia 44 (1997), S. 135-144 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Oligomeric stationary phases ; Enthalpy-entropy compensation ; Methylene and phenyl selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of temperature and mobile phase composition (methanol-water) on the retention behaviour of an oligomeric series of n-octylsilyl bonded phases in reversed-phase liquid chromatography has been investigated. Plots of lnk against 1/T (van't Hoff plot) and the enthalpy of transfer (ΔHo) yields linear relationships under the conditions studied. The ΔHo values of the aromatic hydrocarbons and n-alkyl benzoates are higher than those of the polar compounds due to their higher level of interaction with the stationary phase. A linear plot of ΔHo vs. ΔSo suggest that the retention process, which is essentially controlled by non-specific (dispersive) interactions between the solutes and the bonded ligands, is identical for all cases evaluated. The existence of similar retention mechanisms is confirmed by the constant value of the enthalpy-entropy compensation temperature of the columns for a given class of componds. As expected, decreasing the methanol content (% v/v) of the mobile phase results in increased eluite retention times. The methylene and phenyl selectivities are found to be independent of the carbon content of the stationary phases and varied only with the eluent composition. In addition to their high stability under aggressive mobile phase conditions as previously reported, the results of this study generally showed that the solute retention process on oligomeric phases are similar to those exhibited by the conventional reversed phases.
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    URL: http://dx.doi.org/10.1007/BF02466447
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  • 20
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    Electronic Resource
    Determination of drug-protein interactions by combined microdialysis and high-performance liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 205-208 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microdialysis ; Carbamazepine ; Human serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and rapid method for determination of the parameters of the interaction between drugs and protein, including the association constant and the number of binding sites, has been developed by use of a microdialysis sampling technique combined with high-performance liquid chromatography. The drug and protein (carbamazepine (5H-dibenz[b,f]flazepine-5-carboxamide, CBZ) and human serum albumin (HSA) were used as examples) were mixed in different molar ratios in 0.067 M potassium phosphate buffer, pH 7.4, and incubated at 37°C in a water-bath. The microdialysis probe was the used to sample the mixed CBZ-HSA solution at a perfusion rate of 1 μL min−1. The concentration of CBZ in the microdialysate was determined by reversed-phase high-performance liquid chromatography. Relative recovery (R), determined in vitro under similar conditions, was approximately 42.7%; theRSD ofR was approximately 1.85%. The estimated association constant (K) and the number of the binding sites,n, on one molecule of HSA were 1.06×104 M−1 and 0.880, respectively, which is in good agreement with the literature values determined by high-performance frontal analysis. The potential use of microdialysis is also discussed.
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    URL: http://dx.doi.org/10.1007/BF02466457
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    Interactions between cisplatin derivatives and mobile phase during chromatographic separation (1997)
    Springer
    Chromatographia 44 (1997), S. 19-24 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cisplatin stability ; Cisplatin metabolites ; Platinum phosphato-derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Althoughcis-dichlorodiammineplatinum(II) (cisplatin or CDDP) is widely used for the treatment of several kinds of tumour, its stability and metabolism in biological fluids have not been completely elucidated. Conditions in which mobile phases of formic or phosphoric acids interact with platinum derivatives during chromatographic separation performed by high performance liquid chromatography on-line with inductively coupled plasma-mass spectrometry (ICPMS) are investigated. During chromatographic separation of CDDP the formic acid mobile phase does not interact with CDDP itself nor with its hydrolysis products. In contrast, the phosphoric acid mobile phase interacts, not with the CDDP itself, but with its hydrolysis products which are present only in an aged aqueous solution, to generate two platinum phosphato-derivatives. This study suggests that the phosphoric acid has greater affinity for the CDDP hydrated complexes than formic acid and the latter is more appropriate for the study of cisplatin behavior in aqueous and biological media.
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    URL: http://dx.doi.org/10.1007/BF02466510
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    Porous graphitic carbon (PGC) high-performance liquid chromatography of diphosphine-bridged complexes with heteronuclear Au-M (M=Mn, Re) bonds (1997)
    Springer
    Chromatographia 44 (1997), S. 381-385 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitic carbon ; Diphosphine complexes ; Gold, rhenium, manganese organometallics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The isocratic high-performance liquid chromatography of 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(diphenylphosphino)ruthenocene (dppr), bis(diphenylphosphino)methane (dppm) and triphenylphosphine (PPh3)-substituted heterometallic Au-Mn or Au-Re carbonyl complexes is reported. A column packed with PGC (porous graphitic carbon) was used after preliminary experiments had shown that silica- and bonded-phase (silica-based) stationary phases were unsatisfactory for separation. The PGC column exhibited unique selectivity for the complexes studied. The mobile phases used were water-acetonitrile, dichloromethanehexane and tetrahydrofuran-hexane. The retention behaviour of the compounds was governed by the polar character and size of molecules, and influenced by metal-metal bond polarity. Separation of isomorphous structures with different metallocenyl moieties was achieved.
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    URL: http://dx.doi.org/10.1007/BF02466314
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    HPLC analysis of boldine in pharmaceuticals (1997)
    Springer
    Chromatographia 44 (1997), S. 619-622 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Boldine in pharmaceuticals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for extraction, separation, identification and quantitative measurement of boldine (I) in pharmaceuticals. The extraction of (I) from the matrix (syrups, tablets, extracts) was realized with aqueous ammonium chloride (0.02 M, pH=3.0 with perchloric acid) and the clean-up of the extract was performed by solid-phase extraction by means of cartridges containing a strong cation-exchange sorbent, from which (I) was eluted with aqueous ammonium chloride (1 M, pH=10.0 with ammonia). The final eluate was examined by HPLC. Chromatography was performed on a C-8 column with a gradient elution from 15:85 to 30:70 of acetonitrile-water containing 0.1 M sodium perchlorate (pH=3.0), in 20 min. A diode array detector was used at 302 nm for detection. The method gives recovery values greater than 98% and the reproducibility is within 6.0%.
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    URL: http://dx.doi.org/10.1007/BF02466665
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    An exprimental design approach to selecting the optimum liquid chromatographic conditions for the determination of vitamins B1, B2-phosphate, B3, B6 and C in effervescent tablets containing saccharin and sunset yellow FCF (1997)
    Springer
    Chromatographia 44 (1997), S. 634-644 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin B and C in tablets ; Experimental design ; Optimization of separation ; Multiple regression modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ion-pair liquid-chromatographic separation of the water-soluble vitamins thiamine mononitrate, riboflavin phosphate, nicotinamide, pyridoxine hydrochloride, ascorbic acid, saccharin, and the dye Sunset Yellow FCF (E110) has been examined for the analysis of the compounds in effervescent tablets. A Draper-Lin small composite design was used to study the impact on the compounds' retention times and peak-widths (the response variables) of four different mobile phase variables: percentage of methanol as organic modifier, the concentrations of hexanesulfonate as ion pairing reagent and of triethanolamine as competitive base, and pH. The interactions of these variables were also studied. The proposed design enabled derivation of multiple linear regression equations to model each compound's retention time and peak-width at half-height. The statistical reliability of the regression models was established by comparing predicted and experimental values. By introducing the regression models into a spreadsheet program (Excel 5.0), retention times and peak-widths for each compound were calculated at fixed mobile phase pH. The values of all the other combinations of the three mobile phase variables were changed in increments of two units within their examined boundaries, resulting in 225 different rows. For each combination the compounds' calculated retention times and their corresponding peak-widths were sorted in increasing order and the resolution between successive peaks was calculated. The minimum effective resolution (R s min) between each pair of peaks and the maximum retention time (t R max) in each row were then selected and used to construct contour plots indicating the location of zones of mobile phase parameter combinations whereR s min〉1.5 and the analysis was rugged, and wheret R max values were minimum. Their common regions resulted in optimum chromatographic separations. Examples are shown of chromatographic separations obtained using mobile phase combinations which were the best compromise of the three criteria selected.
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    URL: http://dx.doi.org/10.1007/BF02466667
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    Determination of clenbuterol in urine by azo-dye precolumn derivatization and micellar liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 145-150 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thermal lens spectrometric detection ; Diazotization and coupling derivatization ; Clenbuterol in urine ; N-(Naphthyl)ethylenediamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Clenbuterol has been determined in urine by solidphase extraction on a C18 cartridge, diazotization of the eluate with nitrite, coupling of the diazonium ion with 1-(naphthyl)ethylenediamine, and separation of the azo dye formed by HPLC with a C18 column and a micellar mobile phase containing 0.1 M sodium dodecyl sulphate, 12%n-butanol and 0.05 M citrate buffer, pH 3. Recoveries higher than 90% were obtained by mixing the samples with a 20% 0.2 M NaOH before extraction. Limits of detection of 51 and 6.7 ng L−1 were obtained with spectrophotometric and thermal lens spectrometric detection, respectively; respective repeatabilities were 3.1% (5 μg mL−1) and 5.6% (0.16 μg mL−1).
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    URL: http://dx.doi.org/10.1007/BF02466448
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    Simple and rugged SPE method for the determination of tetracycline antibiotics in serum by HPLC using a volatile mobile phase (1997)
    Springer
    Chromatographia 44 (1997), S. 187-190 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Tetracycline in serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and rugged SPE method for the determination of tetracycline (TC), minocycline (MC) and demeclocycline (DCC) in porcine serum by high performance liquid chromatography (HPLC) was developed. The spiked serum sample was pretreated with 2% phosphoric acid followed by a simple and rugged solid-phase extraction procedure using the OasisTM HLB extraction cartridges. High and reproducible recoveries were obtained even though the cartridges were run dry. The extracted sample analytes were injected onto a Waters SymmetryShieldTM RP8 column. The mobile phase was a simple volatile solution containing 0.1% TFA, 2% methanol and 7% acetonitrile in Water. The antibiotics were detected at 350 nm. The calibration curves were linear from 2.0 to 25.0 μg mL−1 of TC and MC with DCC as the internal standard at a concentration of 25.0 μg mL−1. For six replicate analyses, the average recoveries of TC and MC from porcine serum sample fortified at the level of 2.5 μg mL−1 were 96.1% with 1.3% RSD and 101% with 0.54% RSD; at level of 0.5 μg mL−1 the average recoveries were 88% with 1.6% RSD and 97.8% with 1.4% RSD.
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    URL: http://dx.doi.org/10.1007/BF02466454
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    Uptake of hydrophobic amino acids and sodium chloride by a strong cation exchanger: Application to desalting and separation by preparative liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 240-246 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separations ; Strong cation-exchange resin ; Amino acids ; Desalting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The uptake of sodium chloride, leucine and phenylalanine by a strong cation-exchange resin in the sodium form have been compared. Sodium chloride was excluded from the resin, as indicated by its parabolic upwards curved isotherm, and the corresponding desorption edge was sharpened (constant pattern). Isotherms for both amino acids constructed from a single elution experiment displayed slightly downwards curvature; the corresponding desorption edges spread in contrast to the breakthrough ones. The affinities of both amino acids for the resin were higher (from 15 to 40 %) in the presence of 1 M sodium chloride, indicating that hydrophobic interactions played a significant role in the mechanism of sorption. As expected from the isotherms, a mixture of 1 M sodium chloride, leucine and phenylalanine was separated with satisfactory recovery of both amino acids for a column loading of 10 % of the bed volume. Real mother liquors have also been separated under the same conditions.
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    URL: http://dx.doi.org/10.1007/BF02466388
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    The role of mobile-phase pH in the determination of catecholamine-related compounds by reversed-phase liquid chromatography with amperometric detection (1997)
    Springer
    Chromatographia 44 (1997), S. 348-354 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Catecholamine-related compounds ; pH optimization of mobile phase ; Amperometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A study was conducted for the optimization of the reversed-phase high performance liquid chromatographic separation of different types (acidic, basic, amphoteric and neutral) of catechol-related compounds by varying the pH. For pH to be used as the optimizing parameter, its effects on retention, peak width and peak shape had to be investigated. Therefore, the pH dependence of the amperometric detector response, as measured by the oxidation peak height or peak area, was taken into account.
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    URL: http://dx.doi.org/10.1007/BF02466309
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    Chemical modification of the polymeric sorbent containing hydroxyl functional groups (1997)
    Springer
    Chromatographia 44 (1997), S. 25-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous copolymer with hydroxyl groups ; Chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Dimethyldichlorosilane and stearic acid chloride were used for deactivation of hydroxyl functional groups present in the skeleton of the methacrylic ester ofp,p′-dihydroxydiphenylpropane diglycidyl ether-divinylbenzene, porous copolymer used as HPLC packing. The influence of chemical modification on the chromatographic behaviour of the copolymer was studied. To characterize selectivity of the packings, retention indices of five homologous series and test compounds were determined. The data obtained suggest that modification with stearic acid chloride affects both the chemical and porous structure of the copolymer while modification with dimethydichlorosilane changes only the chemical character of the packing.
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    URL: http://dx.doi.org/10.1007/BF02466511
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    Influence of mobile phase conditions on the clean-up effect of restricted-access media precolumns for plasma samples injected in a column-switching system (1997)
    Springer
    Chromatographia 44 (1997), S. 589-594 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column-switching systems ; Restricted-access media precolumns ; Mobile phase composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Various mobile phases including phosphate buffer, pure water and five kinds of biological buffers (pH around 7) were systematically studied in terms of their ability to clean-up plasma matrix on precolumns of restrictedaccess media in a column-switching system. The necessary washing time, buffer pH, type and content of organic modifier were evaluated with respect to plasma elution profiles on restricted-access media precolumns. The influence of different mobile phases on the recovery of plasma matrix from alkyl-diol silica precolumns was studied by means of a scanning spectrophotometer. Our results show that phosphate buffer near physiological pH with small amounts of 2-propanol or acetonitrile was prefereble for direct injection of large plasma volumes (500 μL). More than 93% of the proteins in a plasma matrix can be recovered within 3 min from the alkyl-diol silica C18 column (25 mx 4 mm I.D.) as measured at 280 nm for all selected mobile phases except for tris (hydroxymethyl) aminomethane buffer, from which only about 88% was obtained.
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    URL: http://dx.doi.org/10.1007/BF02466660
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    Analysis of azines and diazines by HPLC on bonded alkyl stationary phases. Pyridine and quinoline in environmental samples (1997)
    Springer
    Chromatographia 44 (1997), S. 253-256 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Environmental samples ; Azines and diazines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several heterocyclic compounds have been investigated by HPLC on RP-8 and RP-18 with methanol-water mixtures as mobile phase. The chromatographic systems developed showed good selectivity for determination of azines and diazines. Pyridine and quinoline have been determined in environmental samples and in food. Samples for analysis were preconcentrated by solid phase extraction on-column with octadecyl silane packing.
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    URL: http://dx.doi.org/10.1007/BF02466390
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    Polysiloxane-encapsulated stationary phase for reversed-phase high-performance liquid chromatography (1997)
    Springer
    Chromatographia 44 (1997), S. 263-266 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Encapsulated stationary phase ; Poly(methylvinylsiloxane)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica beads of 6-μm average diameter were silanized with methylvinyldiethoxysilane and then subjected to encapsulation with poly(methylvinylsiloxane). The resulting product is a new stationary phase for reversed-phase high performance liquid chromatography (RP-HPLC) which has superior ability for the separation of polar, non-polar and basic compounds. The chromatographic peaks are symmetric. Its stability has been studied; after continuous use for three months the carbon content and chromatographic behaviour of the phase were unchanged. on to the silica surface to given an uniform organic film. Material prepared in this way has both good chromatographic behaviour and superior selectivity. Because contact of the silica matrix with the mobile phase is avoided, the alkali-resisting ability of the stationary phase is increased. The non-specific adsorption of alkaline solutes on to the silica surface is also avoided because of the complete coverage of surface silanol groups. Reports of stationary phases encapsulated with polystyrene [6], polybutadiene [I] and octadecylsiloxane polymers have recently appeared in the literature [3]. In this paper we report the encapsulation of poly-(methylvinylsiloxane) (analogous to the phase SE-31 often used in GC) on to a silica matrix previously modified with methylvinyldiethoxysilane. The resulting phase has superior performance in reversed-phase HPLC.
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    URL: http://dx.doi.org/10.1007/BF02466392
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    Reversed-phase high-performance liquid chromatographic separation of mono- and divinyl chlorophyll forms using pyridine-containing mobile phases and a polymeric octadecylsilica column (1997)
    Springer
    Chromatographia 44 (1997), S. 43-49 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mono-and divinyl chlorophylls ; Polymeric ODS phases ; Pyridine containing mobile phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of chlorophyll forms was studied employing a wide bore polymeric octadecylsilica column and pyridine containing mobile phases, giving consideration to considering the influence of mobile phase composition and column temperature on the resolution of monovinyl forms from their divinyl analogues. A method involving gradient elution and operating at 15°C is proposed for the separation of several polar and non-polar mono- and divinyl chlorophylls from etiolated tissues of higher plants and from marine phytoplankton. The advantages of pyridine as a mobile phase additive in the reversed-phase liquid chromatography of chlorophylls are discussed.
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    URL: http://dx.doi.org/10.1007/BF02466514
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    Optimisation of chromatographic separations by use of a chromatographic response function, empirical modelling and multivariate analysis (1997)
    Springer
    Chromatographia 44 (1997), S. 74-80 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Optimisation ; Multiple linear regression ; Neural networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chiral separation of the drug substance R,S-oxybutynin chloride on a reversed phase HPLC system has been optimised by use of empirical modelling and multivariate analysis. The separation was characterised by a new chromatographic response function developed to modulate both quality of separation and retention time. The study includes a comparison between three different multivariate techniques (multi-layer feed-for-ward neural networks, multiple linear regression and partial least squares regression) of their capabilities to model the new chromatographic response function and predict its value for new experiments. It was indicated that the most accurate models were achieved with neural networks, although partial least squares regression could also be used to solve the problem since it gives the major directions for the optimal settings of the variables.
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    URL: http://dx.doi.org/10.1007/BF02466519
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    Ultrasonic extraction and LC determination of linear alkylbenzene sulfonate in plant tissues (1997)
    Springer
    Chromatographia 44 (1997), S. 417-420 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Plant tissues ; Linear alkylbenzene sulfonate (LAS) ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method has been developed for the extraction and determination of linear alkylbenzene sulfonate (LAS) in plant tissues (rice stems and leaves). It consists of methanol-ultrasonic extraction followed by clean-up with aluminum oxide, enrichment with C18 solid-phase extraction column and determination by HPLC. Both efficiency and accurracy of the overall method were high, i.e. mean recovery of: 89% (84 to 93% for LAS concentrations ranging from 1 to 100 mg kg−1) and repeatability of: 3% relative standard deviation for 6 replicate analyses. With a 2 g sample for analysis, LAS levels of 0.5 mg kg−1 in plants could be detected with the proposed method. Further advantages were: it was less time consuming (1 h for extraction), less solvent consumption, and smaller samples (2 to 3 g) required when compared with Soxhlet extraction.
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    URL: http://dx.doi.org/10.1007/BF02466320
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    Analysis of semipermanent hair dyes by HPLC with on-line post-column photochemical derivatisation (1997)
    Springer
    Chromatographia 44 (1997), S. 431-437 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photochemical derivatisation ; Semipermanent hair dyes ; Cosmetic formulations ; Stability study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The development of a selective and sensitive HPLC method for the determination of semipermanent hair colorants in cosmetic formulations is proposed. The separation and identification of N-hydroxyalkyl nitrophenylenediamines and nitroaminophenols were performed by HPLC with on-line, post-column, photochemical derivatisation, using a reversed phase, ion-pair system with 1,8-diaminooctane and heptansulfonate in the mobile phase. Two UV spectra (photoreactor on and off) were obtained for each analyte, adding information for confirming peak identity. Analyte-modified spectral properties were used to increase the method sensitivity. The proposed method was successfully applied to quality control and stability studies of cosmetic formulations.
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    URL: http://dx.doi.org/10.1007/BF02466323
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    Chromatographic properties in normal-mode HPLC of chiral stationary phases based on substituted β-cyclodextrins (1997)
    Springer
    Chromatographia 44 (1997), S. 411-416 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Bonded substituted cyclodextrins ; Normal mode separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Substituted β-cyclodextrin chiral stationary phases having different types of phenyl carbamate substituents have been prepared and evaluated (retention, selectivity, resolution) for the liquid chromatographic separation of several series of enantiomers. The influence on separations of the degree of substitution and the structure of the substituent are discussed. Different mechanisms are suggested to explain separations in normal mode conditions.
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    URL: http://dx.doi.org/10.1007/BF02466319
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