The identification of 5,6-dihydrouridine in normal human urine by combined gas chromatography/mass spectrometry

The identification of 5,6-dihydrouridine in normal human urine is reported. Partial purification and isolation of the compound by boronate gel affinity chromatography and reversed-phase high-performance liquid chromatography preceded its characterization as a trimethylsilyl derivative by combined gas chromatography/mass spectrometry. Structure proof is based upon a comparison of mass spectral and chromatographic features of the urinary component to that of an authentic reference sample. Additional data derived from high resolution mass measurements and deuterium isotopelabeling experiments provide confirmation of fragment ion structure. The poor detectability inherent in the HPLC uv analysis of nucleosides is also discussed.