Determination of chlorinated pesticide residues in foods. I. Rapid screening method for chlorinated pesticides in milk.
A rapid analytical method for determining chlorinated pesticide residues in milk was developed. Thirteen pesticides were almost completely extracted. Ten mL samples of fortified milk were extracted 3 times with 20 mL portions of n-hexane as follows: (A) in the absence of water-soluble solvent; in the presence of (B) 1 mL acetonitrile; (C) 3 mL acetonitrile; (D) 5 mL acetonitrile; (E) 5 mL ethanol; (F) 5 mL acetonitrile and 1 mL ethanol. System F produced the highest pesticide recoveries but the lowest fat extraction, thus eliminating the necessity for liquid-liquid partitioning and minimizing Florisil column cleanup. Pesticide recoveries throughout the procedure were 94--103%. It was noticed, however, that the fat in high fat-containing raw milk is more readily extracted than that in commercial milk.
D000818:Animals; D001322:Autoanalysis; D002417:Cattle; D002849:Chromatography, Gas; D005223:Fats / Q000302:isolation & purification; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides / Q000032:analysis*; D008892:Milk / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis*
D005223:Fats; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides; D010573:Pesticide Residues