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 de termine 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 sampl es, resulted in repeatability relative standard deviations of 2-8% and repr oducibility relative standard deviations of 4-10%. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.