Submitted to: Analytical Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2010
Publication Date: 7/10/2010
Citation: Chen, P., Wolf, W.R., Castanheira, I., Sanches-Silva, A. 2010. A LC/UV/Vis method for determination of cyanocobalamin in multivitamin dietary supplements with on-line sample clean-up. Analytical Methods. 2:1171-1175. Interpretive Summary: The purpose of this study was to develop a Single-Lab Validated Method using two-column high-performance liquid chromatography (HPLC) with diode array detector for determination of cyanocobalamin (vitamin B12) in multivitamin/multimineral dietary supplements in the U.S. Single Lab Validation was carried out using the National Institute of Standards and Technology (NIST) standard reference material 3280 - MultiVitamin/MultiMineral Tablet, being jointly developed with NIST, with partial support by the Office of Dietary Supplements/National Institutes of Health. Compared to the currently available method, the new method is faster, more economical, and less labor-intensive.
Technical Abstract: A HPLC-UV method using a two-column strategy with a switching valve for on-line sample clean-up was developed for the determination of cyanocobalamin (CN-CBL-vitamin B12, in dietary supplements. The method uses two columns, an Agilent Zorbax C8 (150 mm x 4.6 mm, 5 um particle) reversed-phase column and a Waters Symmetry C18 (150 mm x 4.6 mm, 5 um particle) reversed-phase columns). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) 0.1% formic acid in water and (B) 0.1% formic acid in acetonitrile. A switching valve was used to divert most interference materials to waste. The recovery of CN-Cbl in the method was 99.5% and the limit of quantitation (LOQ) was 10 ng per injection. The method was successfully applied to the analysis of the standard reference material (SRM) 3280 multivitamin/multimineral dietary supplement tablets from the National Institute of Standards and Technology (NIST). The method is specific, precise, and accurate for the intended use. Compared to off-line sample clean-up procedures, it offers the advantages of being easier, more economical, and less time-consuming.