Determination of niacin metabolites 1-methyl-5-carboxylamide-2-pyridone and n-1-methylnicotinamide in urine by high-performance liquid chromatography

A test suitable for detecting latent niacin deficiency was developed. It measures the 24-h urinary output of the two major metabolites of niacin, 1-methyl-5-carboxylamide-2-pyridone and N-1-methylnicotinamide. The two metabolites were isolated from urine using separate ion-exchange extractions. They and their two internal standards were quantitated simultaneously by high-performance liquid chromatography using a reversed-phase ion pairing separation. Detection was by absorbance at 254 nm.