[On the contamination of milk and milk products with chlorinated hydrocarbons. I. Methods].

A method of gaschromatographic determination of chlorinated insecticides in milk and butter in the presence of PCB's is described. The fatty components were extracted from milk after adding sodium oxalate and ethanol with diethyl ether and petrol ether. The clean up of the extracts was carried out according to a modification of the method of Hadorn and Zürcher with propylene carbonate as a selective solvent.