International interlaboratory study for the determination of the Fusarium mycotoxins zearalenone and deoxynivalenol in agricultural commodities

Twenty-eight laboratories from 12 different countries participated in an interlaboratory study for the determination of the Fusarium mycotoxin zearalenone (ZON) in maize and deoxynivalenol (DON) in maize and wheat employing their usual in-house methods. The aim of this study was to obtain information about the state-of-the-art of ZON and DON analysis in cereals and to support a knowledge and experience exchange between the participating laboratories in the Weld of mycotoxin analysis. Eight different sample types were distributed to the participants, 'blank' materials, spiked samples (102 mug/kg ZON in maize and 475 mug/kg DON in wheat) and naturally-cont aminated maize and wheat. For the final separation and quantification either gas chromatography (GC), high performance liquid chromatography (HPLC), thin layer chromatography (TLC) or enzyme linked immunosorbent assays (ELISA) were employed by the participating laboratories. Coefficients of variation (CV) between laboratory mean results (outliers rejected) ranged from 28 to 41% for ZON and from 32 to 38% for DON. The results are close to the between laboratory CV criteria of 40% for DON and ZON at concentration levels of >100 mug/kg established by the CEN in 1999. A good trueness was obtained for the wheat samples spiked at 475 mug/kg DON. However, a significant deviation at p = 0.01 from the respective target value was observed for the maize samples spiked at 102 mug/kg ZON. The high CVs can be traced back to problems occurring by determination of the concentration of the participants' own calibrant solutions. Addition ally, the variability of the results is strongly influenced by the use of different final separation and quantification procedures.