Rapid Enantiomeric Quantification of an Antiviral Nucleoside Agent (d,l-FMAU, 2‘-Fluoro-5-methyl-β,d,l-arabinofurano- syluracil) by Mass Spectrometry

A novel mass spectrometric method is applied to rapid, accurate (<1%) quantification of chiral Clevudine (l-FMAU, 2‘-fluoro-5-methyl-β,l-arabinofuranosyluracil), a potent antiviral nucleoside agent against hepatitis B virus. Transition metal bound complex ions containing the chiral drug are generated by electrospray ionization mass spectrometry and subjected to collision-induced dissociation. The ratio of the two competitive dissociation rates is related to the enantiomeric composition of the drug mixture, allowing the determination of enantiomeric contamination in the drug.