Third EU MAT intercomparison study on food folate analysis using HPLC procedures

Three samples (milk powder, lyophilized pig's liver and wholemeal flour), a 5-methyltetrahydrofolic acid (5-MTHF) calibrant and two deconjugase enzymes (purified hog kidney and human plasma) were circulated to three laboratories taking part in the study. The objectives were to optimize the deconjugation step in these foods and to improve the between-laboratory agreement in HPLC results for folates. The predominant natural folate form in milk powder was 5-MTHF, together with appreciable amounts of folic acid. In pig's liver 5-MTHF was found to represent about one-third of the total folate content found. For these two foods, results from one laboratory of the sum of the folate vitamers agreed favourably with the microbiological data. 5-MTHF was most successfully determined by all three laboratories. There was little or no agreement found for the other folate vitamers detected. Copyright (C) 1996 Elsevier Science Ltd