DETERMINATION OF OCHRATOXIN A IN BEER

Because of concern about possible transmission of ochratoxin A (OA) fr om contaminated grain adjuncts, development of a sensitive method for its determination in beer was investigated. Solid phase extraction (SP E) on C-18 and silica gel columns in series and on an immunoaffinity c olumn (OchraTest(TM)) were used to obtain extracts for quantitation by reverse phase liquid chromatography with fluorescence detection. The standard curve was linear in the range 2.5-50 pg OA injected and detec tion limits for both methods were of the order 0.05-0.1 ng/ml beer (si gnal to noise 3:1). Per cent recovery of OA from various beer samples spiked at a level of 1 ng/ml averaged 82-100% for three modifications of the SPE method and 97% for the immunoaffinity column method. Forty- one samples of Canadian and imported beers were analysed. Trace levels of OA (less than or equal to 0.2 ng/ml) were detected in 26 samples b y SPE and/or immunoaffinity column methods; there was generally good a greement between the methods. identity of OA was confirmed by methyl e ster formation in five samples cleaned up by the immunoaffinity column procedure.