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This paper describes a method for the analysis of DON and its derivatives in wheat and barley using combination gas chromatography/mass spectrometry (GC/MS). The method has been designed for the analysis of large batch (100 g) samples and single kernels. The sensitivity of the method is 50 ppb (ng/g), and the precision in terms of percent standard deviation lies between 0.0 and 11.1. The percent recovery for 1, 5, and 10 µg/g (ppm) recovered from wheat is 97.2, 88.4 and 87.9% respectively. A comparison of methods was made between two laboratories using GC/EC and our method. There was no significant difference between the results of the two methods. The method is also applicable to 15-acetyldeoxynivalenol (15-ADON) as well as nivalenol (NIV). Standard curves constructed for DON, 15-ADON, and NIV show a linear relationship between 0.025 ng (limit of sensitivity) and 8 ng.

Resistance to mycotoxin contamination was compared in field samples harvested from 45 commercial corn (maize) hybrids and 5 single-cross aflatoxin-resistant germplasm lines in years with high and moderate heat stress. In high heat stress, mycotoxin levels were (4.34 +/- 0.32) x 10(3) microg/kg [(0.95-10.5 x 10(3) microg/kg] aflatoxins and 11.2 +/- 1.2 mg/kg (0-35 mg/kg) fumonisins in commercial hybrids and 370 +/- 88 microg/kg (140-609 microg/kg) aflatoxins and 4.0 +/- 1.3 mg/kg (1.7-7.8 mg/kg) fumonisins in aflatoxin-resistant germplasm lines. Deoxynivalenol was detected (one-fourth of the samples, 0-1.5 mg/kg), but not zearalenone. In moderate heat stress, mycotoxin levels were 6.2 +/- 1.6 microg/kg (0-30.4 microg/kg) aflatoxins and 2.5 +/- 0.2 mg/kg (0.5-4.8 mg/kg) fumonisins in commercial hybrids and 1.6 +/- 0.7 microg/kg (0-7 microg/kg) aflatoxins and 1.2 +/- 0.2 mg/kg (0.5-3.0 mg/kg) fumonisins in aflatoxin-resistant germplasm lines. The results are consistent with heat stress playing an important role in the susceptibility of corn to both aflatoxin and fumonisin contamination, with significant reductions of both aflatoxins and fumonisins in aflatoxin-resistant germplasm lines.

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