Determination of deoxynivalenol in 1991 U.S. winter and spring wheat by high-performance thin-layer chromatography

A thin-layer chromatographic (TLC) method was modified for determination of deoxynivalenol (DON) in 1991 U.S. winter and spring wheat. After extraction with acetonitrile-water (84 + 16) and cleanup on a charcoal-alumina-Celite (7 + 5 + 3) column, acetonitrile was used instead of ethyl acetate to transfer the concentrated extract containing DON. After the extract was evaporated to dryness, the residue was dissolved in methanol and an aliquot was spotted on a high-performance TLC plate. After development with chloroform-acetone-2-propanol (8 + 1 + 1), the plates were sprayed with aluminum chloride solution and heated; DON was quantitated by fluorodensitometry. Average recoveries of DON added to duplicate test portions of wheat at 200, 400, and 800 ng/g were 83, 82, and 72%, respectively. The detection limit was 40 ng/g. The method was applied to 81 test samples of spring and winter wheat. The wheat contained DON levels that ranged from nondetectable to 9330 ng/g (average 1570 ng/g). The results indicate that DON levels were higher in wheat from Missouri, North Dakota, and Tennessee than in wheat from 7 other states. The identity of DON, which was isolated from 21 of the extracts by preparatory TLC, was confirmed by gas chromatography/mass spectrometry in all 21 test samples.