Simultaneous determination of nicotinic acid and its metabolites in rat urine by micellar electrokinetic chromatography with photodiode array detection.

Nicotinic acid, nicotinamide and their possible metabolites were successfully separated within 17 min by micellar electrokinetic chromatography using 50 mM borate buffer (pH 9.0) containing 150 mM sodium dodecyl sulfate as the running buffer. Calibration curves for all compounds showed good linearity in a range of 5 microg/ml and 250 microg/ml with good correlation. The present method did not require any clean-up procedures and made it possible to determine all metabolites without interference on a photodiode array detector. Urine samples collected from Wistar male rats were analyzed after high-dose oral or intravenous administration of nicotinic acid or nicotinamide. Metabolic pathways of nicotinic acid in male Wistar rats are also discussed.