A new system of functional foods, which was instituted by Consumer Affairs Agency, Government of Japan, has been put into effect in April 2015. In this system, foods containing functional substances, whose functions for the human body are demonstrated scientifically, are defined as “Foods with Function Claims”, and are allowed to be sold with the information about their functions. Since the amount of functional substances affects the quality and safety of these functional foods, the manufacturers are obliged to submit the accurate amount of functional substances in the foods with the analytical method. High performance liquid chromatography (HPLC) is usually adopted as the analytical method for the determination of functional substances because of its high selectivity and quantitative capability. Lutein, one of natural carotenoids, is reported to have effect to prevent human macula from damages causing by light, so that lutein-containing Foods with Function Claims are sold with claiming the promotion of eye health. However, the reference material of lutein is not available in the reagent markets so that its accurate amount is difficult to be determined by HPLC and might result in leading to reduce the quality and safety of the Foods with Function Claims. In order to solve this problem, the contents of lutein in Foods with Function Claims determined by HPLC and 1H qNMR methods were compared. As the result, the amount determined by HPLC tended to be larger than that by 1H qNMR. One reason for this was that the absolute purity of lutein reagent was lower than the purity, which was calculated using already-known absorption coefficient of lutein. For more accurate calculation of purity of lutein reagent, the absorption coefficient of lutein was also determined by 1H qNMR method, revealing that absorption coefficient of lutein was 2591, which was larger than known value.
