Optimization and validation of an LC-fLD method for biotin in infant formula, infant cereals, cocoa-malt beverages, and clinical nutrition products.

A fast and simple chromatographic method to determine biotin in foods is presented. Biotin is extracted using papain (60°C, 1 h). After pH adjustment and filtration, biotin is determined by LC with fluorescence detection using postcolumn reagent avidin-FITC (avidin labeled with fluorescein isothiocyanate). The method has been validated in a large range of products: milk- and soy-based infant formulas, cereals, cocoa-malt beverages, and clinical nutrition products. The method showed recovery rates of 98.1 ± 5.7% (average ± SD) in a large range of concentrations. Biotin concentrations determined in infant formula standard reference materials 1846 and 1849 were in agreement with reference values. RSD of repeatability (RSD r ) varied from 2.0 to 4.5%, and intermediate reproducibility (RSD iR ) from 5.8 to 9.4%. LOD and LOQ were 3.0 and 5.0 μg/100 g, respectively. The proposed method is suitable for routine analysis of biotin in fortified foods (infant formulas, infant cereals, cocoa-malt beverages, and clinical nutrition products). It can be used as a faster, more selective, and precise alternative to the classical microbiological determination, and is easily transferable among laboratories.