Quantitation of xylose from plasma and urine by capillary column gas chromatography

A specific and sensitive assay for quantitation of xylose from plasma and urine has been developed. Following a clean-up procedure, plasma (0.1 ml) or urine (0.2 ml) samples are concentrated and undergo two sequential derivatization steps. A methyloxime derivative is formed initially, followed by trimethylsilylation of all hydroxyl groups. The derivatized samples are quantitated by capillary column gas chromatography using flame ionization detection. Xylose and the internal standard (2-deoxy-d-ribose) have retention times of 6.5 and 5.2 min, respectively. Other monosaccharides (e.g. ribose, arabinose) do not interfere with the assay. Standard curves are linear and reproducible over a concentration range of 10-200 mg/l for plasma and 100-2000 mg/l for urine. The within-day and day-to-day percentage coefficients of variation were less than 5 and 9%, respectively, for plasma and urine.