Quality of Vitamin B12 Supplements Regarding Vitamin Assay and Content of Heavy Metals

Vegetarians must rely on supplements to meet the recommended daily intake of vitamin B12. Therefore, it is essential to establish a rapid, inexpensive, and reliable method of determining B12 levels in order to accurately characterize and assess the quality of supplements. This study describes a methodology for quantifying vitamin B12 in the form of methylcobalamin and cyanocobalamin following 2 min of ultrasound-assisted extraction performed at pH 4. Vitamin B12 was determined using UV-Vis spectrophotometry and liquid chromatography-tandem mass spectrometry. Thus, LC-MS/MS validated the cost-effective UV-Vis method. The content and form of vitamin B12 in the tested supplements were investigated, and serious discrepancies were found in the content or form of vitamin B12 in three out of ten supplements. To verify the quality of the analyzed supplements, the presence of metal impurities (as Cd, Hg, and Pb) was also assessed using high-resolution continuum source electrothermal atomic absorption spectrometry. No risk associated with the presence of these metals has been noted. Nevertheless, our findings underscore the need for stricter quality control in supplement manufacturing.