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  • Column liquid chromatography  (84)
  • Springer  (84)
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  • 1
    Electronic Resource
    Electronic Resource
    HPLC determination of 18 β-glycyrrhetinic and glycyrrhizinic acids in toothpastes after solid phase extraction (1993)
    Springer
    Chromatographia 35 (1993), S. 167-172 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 18 β-glycyrrhetinic acid ; Glycyrrhizinic acid ; Toothpastes ; Solid phase extraction (SPE)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC methods suitable for the selective and sensitive determination of 18 β-Glycyrrhetinic acid (GT) and Glycyrrhizinic acid (GZ) in toothpastes have been developed. The methods involve a preliminary quantitative solid phase extraction (C-18 sorbent) for sample clean-up and analyte concentration. Chromatographic separations were performed on reversed phase (C-8; C-18) columns using mixtures of methanol and phosphate buffers (pH 3.0) as the mobile phase under isocratic or gradient elution conditions. The method were applied successfully to the analysis of commercial toothpastes containing low levels (0.013–0.065%) of GT and GZ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269697
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of basic hair dyes by HPLC with on-line post-column photochemical derivatisation (1994)
    Springer
    Chromatographia 39 (1994), S. 138-145 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diode array detection ; Post-column photochemical derivatisation ; Hair dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed phase liquid chromatographic method is proposed for the analysis of basic hair dyes (raw materials and colourant formulations). The performance of the method was enhanced by introducing post-column on-line photochemical derivatisation in combination with a Diode Array Detector. On-line photoderivatisation provided an effective way of selectively transforming the analytes to compounds with different spectral properties. For each analyte two characteristic UV-Visible spectra (photoreactor on and off) were obtained with the same mobile phase and this information in combination with the chromatographic data (k' at pH 3.0 and 4.5) enabled the unambiguous identification of both commonly used, approved, and banned basic hair dyes. Additionally, this approach was found useful to improve the method sensitivity, allowing the determination of analytes present in low concentration (0.03%) in complex commercial formulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274492
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  • 3
    Electronic Resource
    Electronic Resource
    1,1′-[Ethenylidenebis(sulfonyl)]bis-benzene: A useful pre-chromatographic derivatization reagent for HPLC analysis of thiol drugs (1996)
    Springer
    Chromatographia 42 (1996), S. 515-520 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol drugs ; Pre-chromatographic derivatization ; 1,1′-[ethenylidenebis(sulfonyl)]bis-benzene reagent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of 1,1′-[ethenylidenebis(sulfonyl)]bis-benzene as a pre-chromatographic reagent for LC analysis of thiol drugs is proposed. The reagent reacts rapidly (2 min) under mild conditions (pH 7.5, ambient) with thiol drugs and the resulting adducts can be chromatographed under reversed-phase conditions (C-18 column). Excess reagent can be removed from the reaction mixture by simple liquid-liquid extraction with chloroform. The HPLC method using UV detection was successfully applied to the analysis of reduced glutathione (GSH), N-acetylcysteine, N-2-mercaptopropionylglycine and captopril in their commercial formulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290285
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  • 4
    Electronic Resource
    Electronic Resource
    An improved extraction of marrubiim fromMarrubium vulgare (1998)
    Springer
    Chromatographia 47 (1998), S. 449-450 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chitin stationary phase ; Marrubiin ; Analgesic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Marrubiin is the main active compound isolated fromM. vulgare, a medicinal plant used in folk medicine to cure several diseases. The present study shows that chitin, an abundant natural polymer, may be successfully in chromatography column to separate marrubiin from complex mixtures. The experimental procedure described here represents an efficient and rapid method to obtain such compound in high yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466478
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  • 5
    Electronic Resource
    Electronic Resource
    Liquid chromatographic behaviour of pyrimidine bases on various bonded phases (1985)
    Springer
    Chromatographia 20 (1985), S. 529-532 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Modified silica gels ; Pyrimidines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of the surface chemistry of bonded-phase column material containing alkyl, phenyl, cyano and amino groups on the adsorption of pyrimidine molecules has been studied by HPLC. The dependence of the retention on the chemical structure of the adsorbed molecules was determined. The influence of the substituents at the pyrimidine ring and their position on the retention character is shown for various bonded phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312171
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  • 6
    Electronic Resource
    Electronic Resource
    A chromatographic method for hydrophobicity investigations of sorbents (1989)
    Springer
    Chromatographia 28 (1989), S. 258-262 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded stationary phases ; Evaluation of the hydrophobicity of sorbents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The energy of interaction (∈0) between the methylene group and the surface of a sorbent is proposed for use in the quantitative evaluation of the hydrophobicity of a sorbent. A method was developed to determine the ∈0 parameter from chromatographic measurements using the investigated sorbent as the stationary phase and linear methylene-containing homologous series, e.g., alkanols, amino-alkanes, etc., as the test compounds. The effectiveness of this method is demonstrated by using, as examples, a series of bonded stationary phases and a series of cross-linked copolymeric sorbents differing in the concentration of the hydrophobic groups. The proposed method is compared with the Martin rule used extensively in the chromatography of oligomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260771
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of glutathione in pharmaceuticals and cosmetics by HPLC with UV and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 23-28 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glutathione ; Pharmaceuticals and cosmetics ; Pre-chromatographic derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A selective HPLC determination of reduced glutathione (GSH) in pharmaceutical and cosmetic formulations is described based on prechromatographic derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxo-2-buteneoic acid. The derivatization reaction is rapid under mild reaction conditions (10 min at ambient temperature and pH 7.5) and the excess reagent can be removed by liquid-liquid extraction. The thiol adducts were chromatographed on a C-8 column using 0.05 M triethylammonium phosphate (pH 4.0) — acetonitrile 68∶32 (v/v), as the mobile phase; UV and fluorescence detection (lem 450 nm, lexc 300 nm) were both used. The structure of the thiol adducts was confirmed by1H and13C NMR spectra using sodium methanethiolate as thiol nucleophile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320453
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of yttrium and lanthanum in zirconium dioxide by HPLC, X-ray fluorescence and neutron activation analyses (1999)
    Springer
    Chromatographia 49 (1999), S. 91-94 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Zirconium oxide ceramics ; X-ray fluorescence ; Neutron activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lanthania-and yttria-stabilized zirconium oxide ceramics have been examined using High Performance Liquid Chromatography (HPLC), thermal neutron activation (NA) and X-ray Fluorescence (XRF) analyses and thus determine the stabilizer content. Ceramic powders with the composition ZrO2:x mol % La2O3 (x=5, 10, 15, 20 and 33) and ZrO2:x mol % Y2O3 (x=10, 15, 20 and 25) were prepared by the citrate and the co-precipitation techniques, respectively. The lanthanum content was determined by HPLC (x=5.09, 9.78, 14.98, 19.81 and 25.94) and NA (x=5.15, 10.32, 17.25, 21.08 and 27.97) analyses, the yttrium content by HPLC (x=8.5, 13.5, 17.9 and 22.1) and XRF (x=9.9, 15.8, 20.1 and 24.9) analyses. An experimental sequence, based on continuous dilution of ceramic powder solutions, is proposed for preparing samples for HPLC measurements. A swimming pool nuclear reactor is used for NA analysis. The quantitative determinations of yttrium and lanthanum doping levels obtained using those techniques are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467194
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  • 9
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466323
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  • 10
    Electronic Resource
    Electronic Resource
    HPLC analysis of basic organic compounds in a multi-component ion-interaction system: A mechanistic study (1998)
    Springer
    Chromatographia 47 (1998), S. 493-500 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-interaction chromatography ; Basic organic compounds ; Diamine modifiers ; Retention mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase HPLC separations of basic compounds have been optimized by use of mobile phases containing 1,8-diaminooctane (DAO) as amine modifier and heptanesulfonate as counter-ion. Such studies have demonstrated the high resolution and selectivity of this chromatographic system compared with mobile phases prepared with the more widely used primary amines. With the aim of clarifying the retention mechanism involved, three sets of compounds with different structures and properties were analyzed: sulfamidics and trimethoprim, aromatic diamines and aminophenols, and a standard mixture of lipophilic basic drugs. The conditions investigated were: diaminoalkane modifier concentration, diaminoalkane modifier alkyl-chain length, nature and concentration of the counter-ion, pH of the mobile phase, concentration of the organic modifer, and the nature of the stationary phase as characterized by percentage carbon loading. Analysis of chromatographic behavior as a function of the chromatographic conditions has enabled the proposal of a mechanism of retention of the three classes of compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467485
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