This European Standard specifies a gas chromatographic/mass spectrometric method for the determination of organochlorine pesticides (OC’s) and polychlorinated biphenyls (PCBs) in animal feeding stuffs and oil. The method is applicable to animal feeding stuffs with a water content up to about 20 wt% and oil/fatty samples containing residues of one or more of the following OC’s and PCBs and some of their isomers and degradation products: - Aldrin; - Dieldrin; - Chlordane (= sum of Chlordane isomers and Oxychlordane); - DDT (= sum of isomers op'-DDT, pp'-DDT, pp'-TDE (pp'-DDD), and pp'-DDE); - Endosulfan (sum of a-/ß-isomers and Endosulfan-sulphate); - Endrin; - Heptachlor (= sum of Heptachlor and ß-Heptachlorepoxide); - Hexachlorobenzene (HCB); - Hexachlorocyclohexane isomers a-HCH (a-BHC), ß-HCH (ß-BHC), ?-HCH (?-BHC or lindane); - PCB 28, 52, 101, 138, 153 and 180 (“Indicator PCBs”) and PCB 198, 209. The method is not yet applicable to Chlorocamphene (Toxaphene), a complex mixture of polychlorinated camphenes. Chlorocamphene has a very distinctive chromatographic profile and is easily recognisable by GC/ECD. Positive identification of the toxaphene isomers can be performed by negative chemical ionisation mass spectrometry (NCI-MS), electron impact tandem mass spectrometry (EI-MSxMS) or electron impact high resolution mass spectrometry (EI-HRMS) [1], which is not within the scope of this method. The limit of quantification for the mentioned organochlorine pesticides and PCBs is 5 ng/g in general. However, 10 ng/g applies for Heptachlor Aldrin, Endrin, Dieldrin, and Endosulfan (a-, ß- and sulphate). Individual laboratories are responsible to ensure that the equipment they used will achieve these limits of quantifications.