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  • Electrochemical detection  (1)
  • Liquid chromatography  (1)
  • Proteomics  (1)
  • 1
    ISSN: 1612-1112
    Keywords: Terbutaline ; Plasma ; Automated HPLC ; Column-switching ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated method based on liquid chromatography has been developed for the determination of terbutaline in human plasma in the range of 5–50 pmole·ml−1. The necessary sensitivity and selectivity was obtained by using electrochemical detection and a microprocessor-controlled column switching system. A combination of three columns was used: a C8 type for pre-separation, a C18 type for trapping and, for final separation, a strongly acidic ion exchanger. The accuracy of the method was examined by comparison with a method based on gas chromatography — mass spectrometry. The overall precision was ±3.5% and ±2.2% respectively at 5 and 50 pmole·ml−1. The total absolute recovery for terbutaline and internal standard at the above concentration levels were in the range 85–106%.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Coupled columns ; Cyclodextrin ; Enantiomers ; Chiral separation ; Bioanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary β-cyclodextrin was used in the mobile phase as chiral selector for separating the enantiomers of terbutaline, chlorthalidone and oxazepam. The effect on chiral resolution using e.g. hydrophobic, polar or cation exchanging stationary phases was investigated. Both the chiral separation factor and retention level were affected by the concentration of methanol and β-cyclodextrin. The stationary phase had no effect on the chiral separation only on the level of retention. By tuning the concentration of β-cyclodextrin and methanol in the mobile phase chiral separation could be obtained on most stationary phases. By changing the stationary phase while adjusting the mobile phase composition to maintain the chiral selectivity, improvements of the selectivity towards e.g. endogenous compounds can be obtained when separating enantiomers in complex matrixes as biological fluids. Further improvement on selectivity can be obtained if coupled columns are used. This is examplified for separation of chlorthalidone and terbutaline enantiomers in biological fluids by coupling an achiral column to another achiral column and using a mobile phase containing β-cyclodextrin on the last column.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Proteomics ; protein analysis ; multidimensional HPLC ; ion-exchange chromatography ; reversed phase chromatography ; comprehensive HPLC ; two-dimensional HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The interactive modes of High Performance Liquid Chromatography (HPLC) of proteins provide a platform for the construction of a multidimensional HPLC system coupled to mass spectrometry. We present a system composed of both anion and cation exchanger columns, in the first dimension, and n-octadecyl bonded 1.5 μm nonporous silica columns in the second dimension. Both columns are operated under gradient conditions. A system suitability test with standard proteins showed that the total analysis can be performed within about 20 minutes. The fractions taken from the ion exchanger column are directly analyzed within one minute on the reversed phase column at a high flow rate. Two reversed phase columns are applied and operated alternatively: while the first column performs the separation within one minute, the analytes leaving the first dimension are enriched in an on-column focusing mode on top of the second column. The sample clean-up and enrichment is performed on a novel type of restricted access cation exchanger column with internal sulfonic acid groups and external diol groups. The columns exhibit a molecular weight exclusion limit for globular proteins of about 15 kDa. Our next studies will be directed towards the analysis of proteins and peptides from extracts of fibroblasts.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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