Certification of B-Group vitamins (B-1, B-2, B-6, and B-12) in four food reference materials

In 1989, the Community Bureau of Reference started a research program to im prove the quality of vitamin analysis in food. To achieve this task, vitami n methodology was evaluated and tested by interlaboratory studies and the p reparation of certified reference materials, which will be used for quality control of vitamin measurements. The main improvements in methodology were achieved by testing and standardizing the extraction condition and enzymat ic hydrolysis procedures. Results for each individual material are derived from five replicate determinations using at least two independent methods: liquid chromatography (HPLC) and microbiological assay for vitamins B-1, B- 2, and B-6; and radioprotein binding and microbiological assays for vitamin B-12. The certificate of analysis for four reference materials gives mass fraction values for water-soluble vitamins. These certified values were bas ed on the acceptable statistical agreement of results from collaborating la boratories. Certified values with uncertainties (mg/kg dry matter) for each CRM are as follows: 4.63 (0.20) and 4.10 (0.51) for vitamins B-1 and B-6, respectively, in CRM 121 (wholemeal flour); 6.51 (0.24), 14.54 (0.3), 6.66 (0.43), and 0.034 (0.003) for vitamins B-1, B-2, B-6, and B-12, respectivel y, in CRM 421 (milk powder); 3.07 (0.17) and 4.80 (0.40) for vitamins B-1 a nd B-6, respectively, in CRM 485 (lyophilized mixed vegetables), and 8.58 ( 0.55), 106.8 (2.8), 19.3 (1.5), and 1.12 (0.044) for vitamins B-1, B-2, B-6 , and B-12, respectively, in CRM 487 (lyophilized pig liver).