Validation of an Analytical Method to Determine the Content of T-2 and HT-2 Toxins in Cereals and Compound Animal Feed by Immunoaffinity Column Clena-up and GC-MS

摘要

A method for the determination of T-2 toxin and HT-2 toxin in cereals and compound animal feed was validated by collaborative study.In short, the method is as follows: A test portion of a sample is extracted with a mixture of methanol/water (80/20, v/v). This raw extract is then diluted, filtered, and applied to an immunoaffinity column. After washing and elution with acetonitrile the eluate is evaporated to dryness. T-2 and HT-2 toxins in the dry residue are then derivatised with N-methyl-N-trimethylsilyl-trifluoroacetamid (MSTFA)/ Trimethylchlorosilane (TMCS) (99/1, v/v), injected into a gas chromatograph, and detected and quantified by mass spectrometry.14 laboratories from 10 different countries were selected to participate in the collaborative study. They received 6 different test materials as blind duplicates. The test materials consisted of a blank cereal mix, two cereal mixes naturally contaminated at different levels, a blank compound animal feed, and two compound animal feeds naturally contaminated at different levels. Furthermore, two blank cereal mixes and two blank compound animal feeds together with specific spiking solutions were provided for recovery determination. The sum of the mass fractions of T-2 & HT-2 after spiking were 50 µg/kg in the cereal mix, and 75 µg/kg in the compound animal feed. Reported apparent recoveries in the cereal mix ranged from 59 to 143% for the sum of T-2 & HT-2 with a mean value of 105%. Reproducibility relative standard deviations (RSDR) for the cereal matrix were 30% at a natural contamination level of ca. 25 µg/kg, 21% at ca. 87 µg/kg, and 27% for the spiked material at 50 µg/kg. For compound animal feed the recovery values ranged from 87 to 145% with 113% for the mean value. The RSDR values were 25% at a natural contamination level of ca. 92 µg/kg, 19% at ca. 125 µg/kg, and 16% for the spiked material at 75 µg/kg. The Horwitz ratios (HorRat) ranged from 0.7 to 1.4.European Commission Regulation 401/2006 [1] lays down method performance criteria for the control of foodstuffs. Even though the validated method applies to cereals and compound feed it meets all of those criteria. Therefore it is suited for official feed control.