Urine by a Reversed- phase High-perfbrmance Liquid Chromatography

er than the normal amount. Especially, it is interesting that nicotinic acid reduces serum cholesterol and triglycerides.i) To study the unknown mechanism, the establishment of a practical method to measure nicotinic acid and its direct metabolite, nicotinuric acid, is important. In l978, Hengen et al.2] measured nicotinic acid and nicotinuric acid in plasma and urine with reversed-phase high-performance liquid chromatography (HPLC), The preparation of plasma and urine is time-consuming (extraction twice by organic solvents and votatilization are included) and losses during the procedure are likely, This method requires fairly large amounts of plasma (O.5 ml) and the analytical methods for urine and blood are diffbrent, In 1982, McKee et aL3) measured nicotinamide, Ni-methylnicotinamide, Ni-