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  • 1
    ISSN: 0173-0835
    Keywords: Fluorogenic reagents ; Peptide ; Fluorescent labeling ; Solid-phase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The fluorescent labeling of peptides at concentrations as low as 10-8 M can be achieved by using a solid-phase reactor. Using oxidized insulin chain B as a test peptide, we demonstrate the use of an Immobilon CD membrane to capture and preconcentrate peptides. Insulin chain B can then be labeled with a fluorogenic reagent, 3-(2-furoyl)quinoline-2-carboxaldehyde, while it is still attached to the membrane. Unwanted fluorescent products (attributed to secondary reactions) can be washed away with methanol without significant removal of the labeled insulin chain B, which then can be extracted with a low pH buffer. The analysis by micellar electrokinetic capillary chromatography with post-column laser-induced fluorescence detection (mass limit of detection of 2.4 × 10-21 moles insulin chain B) results in electropherograms that show great improvement in terms of unwanted peaks and high number of theoretical plates (up to 20 million). The use of the solid-phase reactor allows easy handling of as little as 5 picomoles of insulin chain B.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0173-0835
    Keywords: Antidepressants ; Nonaqueous capillary electrophoresis ; Electrospray mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An on-line nonaqueous capillary electrophoresis-electrospray mass spectrometry (ESI-MS) technique was developed using a commercial ion spray interface. The nonaqueous capillary electrophoresis ESI-MS system was used to profile tricyclic antidepressants of similar structures and mass-to-charge ratios. We found that pure methanol can be used as a sheath liquid to obtain stable ion spray from nonaqueous capillary electrophoresis. The flow rate of the coaxial nebulizing gas affected baseline signals, separation efficiency, and migration times. Other nonaqueous capillary electrophoresis operating conditions and electrospray parameters were optimized for enhanced baseline separation and high sensitivity detection. The effect of sample stacking on separation and detection was evaluated. The calculated detection limits were approximately 3 pg injected onto the capillary. ESI mass spectra of tricyclic antidepressants from a single quadrupole MS were obtained and elucidated. The information was used to propose fragmentation pathways of the tricyclic antidepressants. The method was also used to analyze the metabolites of amitriptyline produced by the fungus Cunninghamella elegans. Sixteen metabolites were detected and most of them were tentatively identified as demethylated and/or hydroxylated, and/or N-oxidized products.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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