Determination of vitamins in food-matrix Standard Reference Materials.

In recent years, the National Institute of Standards and Technology (NIST) has developed several food-matrix Standard Reference Materials (SRMs) characterized for vitamins and other organic nutrients. NIST uses several "modes" for assignment of analyte concentrations in SRMs, one of which includes the use of data provided by collaborating laboratories. Certification modes and liquid chromatographic methods that were used by NIST for value assignment of vitamin concentrations in recently introduced food-matrix SRMs are described in this paper. These materials and methods include vitamins D and E in coconut oil (SRM 1563) by gravimetry and multi-dimensional liquid chromatography (LC); vitamins A, E, and several B vitamins by reversed-phase LC and vitamin C by ion-exchange chromatography in infant formula (SRM 1846); and carotenoids and vitamins A and E by reversed-phase liquid chromatography in a baby food composite (SRM 2383).