Optimization of the determination of deoxynivalenol in corn samples by liquid chromatography and a comparison of two clean-up principles

The determination of deoxynivalenol (DON) in corn by liquid chromatography with DAD detection was optimized. The separations were achieved on a Hypersil ODS column (100 × 4.6 mm; particle size 5 mm) by isocratic elution (0.6 cm3/min), a mobile phase consisting of acetonitrile–water in the ratio of 16:84. UV Detection was performed at 220 nm. Linear calibration curves were constructed in the concentration range of 0.72 – 12.00 ng/ml (equivalent to 0.29 – 4.8 mg/g corn). The detection limit measured as the signal-to-noise ratio (3:1) was 0.16 ng/ml for DON (equivalent to 0.06 mg/g corn). The efficiencies of two clean-up principles for crude corn extract were compared: solid-phase and immunochemical extraction. The efficiency of solid-phase extraction was found to be higher, with a value of 92.7 % when MycoSep 225 columns were used, while its value was 97.6 % when self-made activated charcoal–alumina–Celite–cationic columns were used. In contrast, the efficiency of the immunochemical columns (IMA) was only 73.8%. Itwas also found that the self-made columns could be used at least three times in a row, in that way differing from the MycoSep 225 columns, which could not be reused either with or without regeneration, as well as from the IMA columns, which had a regeneration efficiency of 53.6 %

The content of deoxynivalenol and zearalenone in certain parts of Fusarium infected wheat heads

During the year 2006, climatic conditions were favourable for the appearance of head blight in the majority of localities in which wheat was grown in our country. In the locality of Apatin, in certain plots, the amount of detected infection was up to 25 infected heads per m2. During the harvest, heads with distinct disease symptoms and sporulation of Fusarium graminearum fungi were gathered. Grains from the parts of heads with manifested disease symptoms were separated into separate samples, together with the grains above and below the infested head part. Apart from ocular evaluation, the percentage of grain infestation by Fusarium genus fungi was determined in all three sample categories, using wet chamber method. Deoxynivalenol (DON) was determined in the samples after extraction, using acetonitrile-water (84:16 v/v) solution. Quantitative amount of DON was determined using liquid chromatography with DAD detector at 220 nm. The content of DON in the samples was as follows: grains with manifested disease symptoms 353,4 ppm (μg/g), grains above the infested head part 0,225 ppm (μg/g), grains below the infested part 0,125 ppm (μg/g). The content of zearalenone in the samples was determined using thin layer chromatography method. This toxic agent was determined only in the samples taken from the head part in which disease symptoms were clearly manifested in the amount of 2,1 ppm (μg/g)