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.