Evaluation of Two Extraction Procedures for Pesticide Residues Resulting from Foliar Application and Root Absorption

Abstract

Abstract The acetonitrile extraction procedure of Mills et al. and the 35% water-acetonitrile extraction procedure of Bertuzzi et al. were evaluated for the determination in fresh and dehydrated samples of 4 organochlorine pesticide residues resulting from foliar application or root absorption. Extraction of 2 organophosphorus pesticide residues from fresh samples was also studied. Extraction efficiencies were hased on the amount of pesticide residue removed by exhaustive Soxhlet extraction with chloroform-methanol (1 + 1). Residues resulting from foliar application of aldrin (dieldrin), diazinon, endosulfan (isomers I and II and endosulfan sulfate), methoxychlor, parathion, and TDE to green vegetables were determined after acetonitrile extraction; results ranged from 92 to 104% of the amounts determined after exhaustive extraction. Only one-half to two-thirds of dieldrin absorbed from the soil into potato tubers could be detected after acetonitrile extraction. Acetonitrile alone was not satisfactory for extracting dehydrated samples. When dehydrated samples containing residues resulting from foliar application were extracted with 35% water-acetonitrile, results were comparable to those by exhaustive extraction. However, the water-acetonitrile extraction was also ineffective for root-absorbed residues in the dehydrated samples. Analysis of samples after storage indicated that organochlorine pesticide residues on fresh vegetables undergo little or no change during frozen storage.