USE OF VARIOUS CLEANUP PROCEDURES FOR THE ANALYSIS OF OCHRATOXIN-A INCEREALS

A rapid and reliable procedure has been developed for the determinatio n of ochratoxin A in wheat and oats. The method consists of extraction of the sample with acidic chloroform, followed by defatting with n-he xane and finally, HPLC determination with fluorometric detection. Mean recoveries for wheat and oats spiked at levels between 1 and 100 mu g /kg ranged from 80 to 104%. The limit of determination (field blank +6 sigma) was 0.8 mu g/kg and the precision (within-laboratory relative standard deviation) ranged from 3 to 7%. The method was tested on 34 w heat and 34 oats samples. Ochratoxin A was confirmed in some positive samples by methyl eater formation and/or by clean-up of the extracts w ith immunoaffinity columns. The method was not appropriate for the ana lysis of barley (45 tested samples), rye (69 samples) or trout feed (1 3 samples). A false positive was recorded within the four positive bar ley samples and 18 false positives were recorded within the 21 positiv e rye samples whereas trout feed samples could not be analysed due to insufficient clean-up. The use of immunoaffinity columns made the anal ysis of trout feed and rye samples possible, providing excellent clean -up of the extracts with no false positive results and a good limit of determination (0.2 mu g/kg). (C) 1998 Elsevier Science B.V. All right s reserved.