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  • 1
    Electronic Resource
    Electronic Resource
    Investigation of unexpected migration behavior of adenosine in capillary zone electrophoresis (1998)
    Springer
    Chromatographia 47 (1998), S. 225-229 
    Details
    ISSN: 1612-1112
    Keywords: Capillary zone electrophoresis ; Electrophoretic mobility ; Adenosine ; Nucleoside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capillary zone electrophoresis of two common nucleosides, adenosine and inosine, was investigated. Both compounds were resolved in a 0.1 M sodium phosphate buffer, pH 7.5. Contrary to expectations, adenosine behaved at this pH— 5 pH units lower than the literature pKa— as a negative ion, migrating behind mesityloxide (neutral marker) when working in normal polarity mode. To confirm the migration order, peaks were identified from absorption maxima, by high-speed scanning detector. The change in electrophoretic mobility with pH was investigated for the nucleosides, and 10 other background electrolytes were tried to match the separation capabilities of the sodium phosphate buffer. Most inorganic buffers showed comparable separation, while organic, Good-type buffers lacked selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466586
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Interlaboratory study of analysis of phenoxymethylpenicillin by liquid chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 152-156 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenoxymethylpenicillin ; Collaborative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatography method for analysis of phenoxymethylpenicillin has been examined in a collaborative study involving 6 laboratories. The method comprised an isocratic part, which is used in the assay. When the isocratic part is combined with gradient elution, the method is suitable for purity control. Five samples of phenoxymethylpenicillin (potassium salts and acid) were analysed. The main component, the most important side product 4-hydroxyphenoxymethyl-penicillin and other impurities were determined. An analysis of variance proved the absence of consistent laboratory bias. Laboratory-sample interaction was not significant. Estimates of the repeatability and reproducibility of the method, expressed as standard deviations (SD) of the result of the determination of phenoxymethylpenicillin, were 0.50 and 0.63 respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466574
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of chlortetracycline and related substances by capillary zone electrophoresis: Development and validation (1998)
    Springer
    Chromatographia 48 (1998), S. 576-580 
    Details
    ISSN: 1612-1112
    Keywords: Capillary zone electrophoresis ; Chlortetracycline ; Analysis ; Validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary zone electrophoresis method has been developed and validated for the analysis of chlortetracycline and related substances. The influence of the type of buffer, pH and concentration of the buffer were investigated. In all cases 1 mM EDTA was added to prevent metal ion complexation. Instrumental parameters such as capillary temperature and applied voltage were optimised. The following methods is proposed: capillary: fused silica, 44 cm (36 cm effective length), 50 μm i.d.; buffer: 120 mM sodium tetraborate including 1mM EDTA at pH 8.5; voltage: 10 kV; temperature: 25°C; detection wavelength: 280 nm. The robustness of the method has been examined by means of a full-fraction factorial design. The parameters for validation namely relative standard deviation, linearity, precision, limit of detection and limit of quantitation are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466652
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Liquid chromatography of josamycin on poly(styrene-divinylbenzene) (1995)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 352 (1995), S. 797-800 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An isocratic liquid chromatographic method for the assay and purity control of josamycin using wide-pore poly(styrene-divinylbenzene) as the stationary phase is presented. Josamycin has been well separated from all the related leucomycins, present as impurities in commercial samples. Wide-pore PLRP-S 8 μm 1000 Å has shown the best selectivity. The separation has been carried out at 65°C with a mobile phase of 2-methyl-2-propanol/0.2 mol/l potassium phosphate buffer pH 10.5/water (24.5: 5: 70.5, V/V) and a flow rate of 1.0 ml/min. UV detection has been performed at 232 nm. The total analysis time has been about 40 min. The method has been used to analyse commercial bulk samples and tablets containing josamycin base.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323067
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    Paper (German National Licenses)
    Fulltext
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