DETERMINATION OF AFLATOXINS IN BEER

Aflatoxins B-1, B-2, G(1), and G(2) were determined at parts-per-trill ion levels in beer by immunoaffinity column cleanup and reversed-phase liquid chromatography (LC) with fluorescence detection after trifluor oacetic acid derivatization. Silanized vials were necessary for the ev aporation step in order to obtain good recoveries of aflatoxins from s piked beer samples. Recoveries averaged 90-104%, 94%, 84-87%, and 89% for aflatoxins B-1, B-2, G(1), and G(2), respectively, at levels of 9. 7-133 ng B-1, 46 ng B-2, 35-140 ng G(1), and 41 ng G(2)/L. Detection l imits were 19-20 ng/L for aflatoxins B-1 and G(1) and 15-16 ng/L for a flatoxins B-2 and G(2) (signal-to-noise ratio = 3:1) obtained by using an excitation wavelength of 360 nm; at 340 nm these detection limits were lowered to about 2 ng/L. Analysis of 24 beer samples, the majorit y from the United States and Mexico, showed natural contamination of o ne sample of Mexican beer at 49 ng B-1/L when determined at 360 nm exc itation, but reanalysis of 23 of the samples using 340 nm excitation i ndicated that an additional 4 Mexican samples and one Brazilian sample contained aflatoxin B-1 at low levels (<10 ng/L).