title: Quantitative analysis of 5-fluorouracil and 5,6-dihydrofluorouracil in plasma by gas chromatography mass spectrometry.
abstract: 5-Fluorouracil and 5,6-dihydro-5-fluorouracil were analysed in the plasma of patients by combined gas chromatography mass spectrometry. 5-Bromouracil was the internal standard. After extraction from plasma with an isopropanol-diethyl ether mixture (20/80) the components were pentylated and the derivatives produced extracted into diethyl ether. Electron impact mass spectrometry was used for the simultaneous quantitative determinations of 5-fluorouracil and 5,6-dihydro-5-fluorouracil (detection limit 10 ng ml-1 5-fluorouracil, 80 ng ml-1 5,6-dihydro-5-fluorouracil). Chemical ionization was utilized to measure 5,6-dihydro-5-fluorouracil concentrations less than 80 ng ml-1 (sensitivity 10 ng ml-1). The biological applicability of these two techniques was demonstrated by analysing plasma samples from patients after administration of 5-fluorouracil or 5'-deoxyfluorouridine by intravenous injections and infusions.
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005467:Floxuridine / Q000378:metabolism; D005472:Fluorouracil / Q000097:blood* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D013997:Time Factors; D014498:Uracil / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: C007419:dihydrouracil; D005467:Floxuridine; D014498:Uracil; D005472:Fluorouracil; C025034:doxifluridine