3RD EU MAT INTERCOMPARISON STUDY ON FOOD FOLATE ANALYSIS USING HPLC PROCEDURES

Three samples (milk powder, lyophilized pig's liver and wholemeal flou r), a 5-methyltetrahydrofolic acid (5-MTHF) calibrant and two deconjug ase enzymes (purified hog kidney and human plasma) were circulated to three laboratories taking part in the study. The objectives were to op timize the deconjugation step in these foods and to improve the betwee n-laboratory agreement in HPLC results for folates. The predominant na tural 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 a bout 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 agreemen t found for the other folate vitamers detected. Copyright (C) 1996 Els evier Science Ltd