Estimation of dietary intake of biotin and its measurement uncertainty using total diet samples in Osaka, Japan.

Single-laboratory method performance parameters were evaluated for analysis of biotin in total diet samples by hydrolyzed extraction and microbiological assay with Lactobacillus plantarum. The method was shown to be accurate, repeatable, rugged, and applicable for the determination of biotin in a broad range of matrixes and concentrations of total diet samples. The measurement uncertainty was evaluated with all food sample groups by combining the relative uncertainty of precision, recovery from each food group, and interday variation factors calculated from the ruggedness test results. The estimated daily intake of biotin in Osaka city and its expanded measurement uncertainty were 70.1 +/- 11.2 microg/day. The value was 1.6 times higher than the current adequate intake of biotin in Japan.