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  • 1
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Urea herbicides ; Catalytic hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the rapid catalytic hydrolysis of phenylurea herbicides on silica gel at elevated temperatures. After derivatisation of the anilines produced with heptafluorobutyric acid anhydride final analysis is done on a gas chromatograph equipped with an electroncapture detector. Detection limits are in the 1–5 picogram range. The method has successfully been applied to residue analysis of water samples at the 1 ppb level. The determination of free anilines present in water samples and the potential of various techniques to be used to discriminate between free anilines and parent herbicides are also discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Narrow-bore column liquid chromatography ; Post-column derivatization ; Solid-phase reactors ; Catalytic hydrolysis ; On-line trace enrichment ; Immobilized enzyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of solid-phase reactors for post-column derivatization in narrow-bore HPLC (1.0mm i.d. analytical columns) is evaluated. Two systems are described, viz. for the determination of N-methylcarbamate pesticides and for that of urea and ammonia. The solid-phase reactor is packed with a strong anion exchange resin and urease immobilized on silica, respectively, to effect the catalytic hydrolysis of the solutes eluting from the analytical column. In both systems, the hydrolysis product is reacted with o-phthalaldehyde followed by fluorescence monitoring. Analytical data are presented and band broadening from various parts of the reaction detector system is discussed. An on-line trace enrichment procedure via a micro precolumn is descried for the trace level determination of N-methylcaramates in surface water samples.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Miniaturized HPLC ; Post-Column Extraction Detection ; Segmented-Flow Open-Tubular Reactors ; Membrane Phase Separator ; Anti-Cancer Drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An on-line, post-column, extraction system suitable for use with miniaturized HPLC (0.7–1 mm i.d. columns) is described. The system consists of a 30° angle segmenting tee, a PTFE extraction coil of variable length and a membrane phase separator. The internal volume of the phase separator is less than 1 μl. The total variance contribution of the system is between 1 and 6 sec2. The determination of the anti-cancer drugs VP 16 and VM 26 in urine by means of reversed-phase HPLC and fluorescence detection, using both on-column preconcentration and the present miniaturized post-column extraction system is presented as an application.
    Type of Medium: Electronic Resource
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