HPLC-ESI-MS analysis of Vitamin B12 in food products and in multivitamins-multimineral tablets

Methods for the determination of Vitamin B-12 remain limited due to their low sensitivity and poor selectivity. In the present work, a simple and sensitive HPLC-ESI-MS method for determining Vitamin B-12 in food products and in multivitamin-multi mineral tablets was developed. Vitamin B-12 was extracted from food products with 50 mM sodium acetate buffer (pH 4.0) in the presence of sodium cyanide. Total Vitamin B-12 content in food product can be obtained by efficient enzymatic hydrolysis to release the bound Vitamin B-12. Vitamin B-12 was quantified with ginsenoside Re as internal standard (I.S.) after their separations on a C-18 column with a gradient of mobile phase made of water and acetonitrile. MS with SIR mode at m/z 930.8 was used for Vitamin B-12 quantification. The calibration graphs plotted with five concentrations of Vitamin B-12 was linear with a regression coefficient r(2) = 0.9994. The intra-assay R.S.D. and the inter-assay R.S.D. were 2.6% (n = 5) and 3.5% (n = 6), respectively. The recoveries evaluated at spiking three different concentrations on fortified products were above 93%. The method has been applied successfully in the determination of Vitamin B-12 in fortified food products and multivitamin-multimineral tablets. (c) 2006 Elsevier B.V. All rights reserved.