Submitted to: Journal of Environmental Science and Health
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2007
Publication Date: 6/17/2007
Citation: Aysal, P., Ambrus, A., Lehotay, S.J., Cannavan, A. 2007. Validation of an Efficient Method for the Determination of Pesticide Residues in Fruits and Vegetables Using Ethyl Acetate for Extraction. Journal of Environmental Science and Health B. 42:481-490. Interpretive Summary: Pesticide residues must be analyzed in fruits, vegetables and other foods for food safety and regulatory purposes, but current methods of analysis are too slow, laborious, and wasteful. Better methods of analysis are needed, and this paper describes an adaptation and validation of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for multiclass, multiresidue analysis of pesticides. The adaptation entails the use of a different organic extraction solvent, and the analytical method avoids the need for complicated and expensive instruments. This alternate protocol provides the means for laboratories in developing countries to use the QuEChERS sample preparation method with traditional detection systems. This reduces the cost burden for analysis by regulators and exporters in those countries, and may improve food safety and trade of many food crops.
Technical Abstract: In this study, a version of the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method was modified to use ethyl acetate (EtOAc) rather than acetonitrile (MeCN) for extraction in the determination of multiple pesticide residues in fruits and vegetables. EtOAc is better suited than MeCN for gas chromatographic (GC) analysis with electron capture detection (ECD) and nitrogen-phosphorus detection (NPD). The method entailed extraction of 30 g chopped sample plus 5 g NaHCO3 and 30 g anhydrous Na2SO4 with 60 mL EtOAc using a probe blender. After a centrifugation step, removal of residual water and cleanup were performed using dispersive solid-phase extraction (dispersive-SPE) with MgSO4 and primary secondary amine (PSA) sorbent. 14C-labeled chlorpyrifos with liquid scintillation counting was used to assist in optimizing and characterizing the method, and GC-ECD and GC-NPD were used for analysis of 24 selected pesticides. The method was validated using tomato, apple and frozen green bean matrices spiked at 0.05, 0.5, and 5 mg/kg. For 22 of the analytes, recoveries averaged 93% for all 3 commodities over the validation range with a relative standard deviation of 10% (n=1182). Lower recoveries of dichlorvos were obtained with the method and iprodione determination was compromised in the green beans by an interfering peak. Typical limits of detection were 0.005-0.01 mg/kg with the method.