Abstract
The current situations and problems of vitamin assay for mainly clinical samples were projected and issued in this journal (Vitamins), Vol.85, (3), (5), (6), (7) and (9), and the difference of methods, standardization, standards, certified reference materials and reference values were discussed in the issues. We summarized main four original methods used for analysis of food and mentioned validation of their methods reported so far to confirm whether their methods are established properly. In order to verify whether these methods being used presently are proper, we examined reproducibility within laboratory tests, spike tests and proficiency tests and showed their results. The repeatability was less than 7.7 %, the recovery of spike tests was 94 to 121 % and the Z-score of proficiency tests was -0.9 to 1.2. Therefore, these results allow us to conclude that these methods are proper for analyses of vitamins in food.
