Biosensor-based determination of folic acid in fortified food

A newly developed method for the quantification of folic acid in fortified food is presented. An immunoaffinity-based optical biosensor was used to determine folic acid concentration levels in milk powder, infant formula and cereal samples. Accuracy of the method (88–101%) was demonstrated with the analysis of five reference samples. A collaborative precision study, where ten participants at four different laboratories analysed a set of ten samples, resulted in repeatability relative standard deviations of 2–8% and reproducibility relative standard deviations of 4–10%.