Liquid-chromatographic determination of dolichols in urine.

A reversed-phase "high-performance" liquid chromatographic assay for dolichols-18, -19 and -20 in urine is described. Dolichols are extracted from urine by using C18 cartridges and are chromatographed with a mobile phase consisting of 2-propanol/methanol, the effluent being monitored at 210 nm. The useful lower limit of sensitivity for quantification is 4 pmol (5 ng) of each dolichol per 5-microL injection, corresponding to 1.6 nmol (2 ng) per liter of urine. Heneicosaprenol is satisfactory as the internal standard. Peak heights and the amounts of dolichols applied to the column are linearly related from 4 to 110 pmol. Mean analytical recovery was 71%. For three different concentrations the mean within-assay CV was 6.4%, the between-assay CV 11%. The normal reference interval of total dolichols found for healthy adults was 17-101 micrograms/24 h (n = 30) or 1.9-11 micrograms per millimole of creatinine (n = 39). I determined the distribution of the main dolichols in urine and applied the assay also for samples from alcoholics.