Fluorimetric determination of niacin in foods by high-performance liquid chromatography with post-column derivatization

A method to determine the content of niacin in various foods by liquid chromatography is proposed and includes hydrochloric acid hydrolysis of the sample, pre-column conversion of the different vitamers (NAD, NADP, nicotinamide and nicotinic acid) into nicotinic acid by alkaline hydrolysis, separation on a C18 stationary phase, post-column derivatization by UV irradiation in the presence of copper (II) ions and hydrogen peroxide, and fluorimetric detection. The proposed method leads to a good recovery rate (90–107%) and a satisfactory repeatability (coefficient of variation less than 4%). Owing to its very low quantification limit (0.2 μg g−1) and the excellent resolution of the nicotinic acid peak, it could most probably be applied to the determination of niacin in any foodstuff. ©