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.