CERTIFICATION OF AN ANIMAL FEED REFERENCE MATERIAL FOR THE ORGANOCHLORINE PESTICIDE CONTENTS - BCR CRM-115

An animal feed reference material has been prepared and enriched with 15 organochlorine pesticides at levels close to the maximum residue li mits set up in the European Directive 74/63/EEC. The homogeneity of th e material has been assessed on the basis of the pesticide contents at a level of sample intake of 5 g. The one year stability study reveale d an instability of heptachlor, o,p'-DDT, p,p'-DDT, alpha-HCH and gamm a-HCH (decrease in content) and p,p'-TDE (increase) at +37 degrees C; at +20 degrees C no instability could be demonstrated. The material ha s been certified in an interlaboratory certification study for: HCB (0 .0194 mg/kg), beta-HCH (0.023 mg/kg), gamma-HCH (0.0218 mg/kg), heptac hlor (0.019 mg/kg), gamma-Chlordane (0.048 mg/kg), alpha-Endosulfan (0 .046 mg/kg), Dieldrin (0.018 mg/kg), Endrin (0.046 mg/kg), o,p'-DDT (0 .046 mg/kg) and p,p'-DDE (0.047 mg/kg). The alpha-HCH isomer, Aldrin, beta-Heptachloro-epoxide, p,p'-DDT and p,p'-TDE could not be certified . The methods used for the certification are described as well as the major difficulties encountered in the study.