ANALYSIS OF URINARY PSEUDOURIDINE BY MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY

We describe a capillary electrophoresis procedure, using uridine as an internal standard, for the analysis of urinary pseudouridine followin g solid-phase extraction. This method retains the advantages of existi ng chromatographic techniques but has superior resolving power and is technically less demanding. The standard curves were linear and reprod ucible with a detection limit of 60 fmol; chromatographic analysis was complete in under 10 min. Injection variability was <5% and multiple independent analyses of the same urine sample for pseudouridine concen tration gave coefficients of variation of <10%. The mean (SD) urinary pseudouridine level in 18 healthy subjects was 16.1 (2.1) nmol/mu mol creatinine. For a limited group of subjects where samples were taken m ore frequently, intra-individual variation averaged 27.5% reflecting v ariable excretion.