Determination of 1-(beta-D-arabinofuranosyl)-5-(1-propynyl)-uracil and a metabolite, 5-propynyluracil, in plasma using ASTED (automated sequential trace enrichment of dialysates) combined, on-line, with high-performance liquid chromatography.

A high-performance liquid chromatographic assay was developed for the determination of the potential antiviral drug 1-(beta-D-arabinofuranosyl)-5-(1-propynyl)uracil (I) and a metabolite, 5-propynyluracil (II), in plasma. Plasma samples were mixed with monochloroacetic acid to reduce the effect of protein binding. The mixture was dialysed prior to concentration of analytes on an ODS cartridge followed by isocratic separation on an ODS analytical column using acetonitrile in aqueous ammonium acetate. Detection was by ultraviolet absorption. The quantifiable limit for both I and II is 0.2 mumol/l with a mean inter- and intra-assay precision of 1.3-2.5% (coefficient of variation).