Natural Zearalenone Contamination of Wheat from Golestan Province, Northern Iran

Zearalenone contamination of 175 wheat samples produced in 2004 in Golestan province, northern Iran was determined. The 10-20 kg samples collected at different stages, including pre-harvest, before and after storage for 2 months in local silos. Samples were ground and sub-sampled with an analytical Romer mill. Each sample extract was cleaned-up using an immunoaffinity column. Zearalenone levels were determined by high-performance liquid chromatography (HPLC) with UV detection at 275 nm. The linearity of the calibration curve in the range 12.5-750 ng/ml standard solutions of zearalenone was 0.997. The limit of detection (LOD) of the method was 30 ng/g. Mean recovery of the method was 85.5 % and 79 % at spiking levels of 100 and 200 ng/g, respectively. Fifteen samples out of 175 samples (8.6%) were contaminated. Mean level for contaminated samples was 72ng/g and the range of contamination was 39-104 ng/g. The proportion of contaminated samples was low and the levels were lower than the advisory levels for zearalenone in wheat.