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  • 11
    Electronic Resource
    Electronic Resource
    Chemiluminescent lipase determination based on the enhanced luminol/H2O2/horseradish peroxidase/fluorescein diacetate energy transfer system (1999)
    Springer
    Fresenius' journal of analytical chemistry 365 (1999), S. 537-540 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A methodology for the determination of lipase, based on the coupled processes of energy transfer and enhancement of the chemiluminescence of the luminol-H2O2-horseradish peroxidase (HRP) system has been developed. Fluorescein diacetate (FDA) was hydrolyzed to fluorescein by the action of the enzyme lipase, and this compound acted as an enhancer of the chemiluminescent process and acceptor of the chemiluminescent emission from the luminol-H2O2-HRP system. By measuring the transferred emission to fluorescein at 525 nm, lipase (range 0.2–1.5 U/mL, RSD 2.3%) was determined. This methodology permited the determination of every compound of the system, thus, H2O2 (range 0.5–2 mM, RSD 6.9%) and HRP (range 5.5–49.5 U/mL, RSD 3.6%) could also be determined. Lipase was determined in rabbit serum with 96.7 ± 3.3% and 102.9 ± 5.4% recoveries for two different lipase concentrations. Besides, H2O2 was determined in the disinfectant solution for contact lenses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051518
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  • 12
    Electronic Resource
    Electronic Resource
    Enzymatic determination of fenitrothion by cholinesterase and acetylcholinesterase on fluorogenic substrates (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 958-961 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The action of the enzymes acetylcholinesterase and cholinesterase on the substrates indoxylacetate and 2-naphthyl acetate was studied kinetically. Both enzymes convert the substrates to highly fluorescent products (3-hydroxy-indole and 2-naphthol, respectively). The kinetic curves present the initial rate as the variation of fluorescence for a unity of time (ΔF/Δt) against the substrate concentration. This enzymatic reaction was investigated in presence of the inhibitor organophosphate pesticide fenitrothion. From the kinetic curves the enzymatic parameters and enzyme and substrate concentrations used for the calibration curve can be obtained. Four simple spectrofluorimetric methods for the enzymatic determination of fenitrothion were developed showing detection limits between 5.5 to 19.5 μmol/l, depending on the enzyme and the substrate used. The precisions (R.S.D.) of the methods were between 1.6 and 9.6%. A comparative study of the kinetic enzymatic parameters and the detection limits was performed. A good correlation was obtained between inhibition constants and the detection limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050281
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    Paper (German National Licenses)
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  • 13
    Electronic Resource
    Electronic Resource
    Enhancer effect of fluorescein on the luminol-H2O2-horseradish peroxidase chemiluminescence: energy transfer process (1997)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 12 (1997), S. 199-205 
    Details
    ISSN: 0884-3996
    Keywords: luminol ; fluorescein ; enhancement chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The chemiluminescence of the luminol-H2O2-horseradish peroxidase system is increased by fluorescein. Fluorescein produces an enhancement of the luminol chemiluminescence similar to that of phenolphthalein, by an energy transfer process from luminol to fluorescein. The maximum intesity and the total chemiluminescence emission (between 380 and 580 nm) of luminol with fluorescein was more than three times greater than without fluorescein; however, the emission duration was shorter. The emission spectra in the presence of fluorescein had two maxima (425 and 535 nm) and the enhancement was dependent on pH and fluorescein concentration. A mechanism is proposed to explain these effects. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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