|De Kok, Andre|
|Van Bodegraven, Peter|
Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2004
Publication Date: 3/29/2005
Citation: Lehotay, S.J., De Kok, A., Hiemstra, M., Van Bodegraven, P. 2005. Validation of a fast and easy method for the determination of 229 pesticide residues in fruits and vegetables using gas and liquid chromatography and mass spectrometric detection. Journal of Association of Official Analytical Chemists International. 2005. v. 88. p. 595-614. Interpretive Summary: Pesticide residue analysis of foods is a main function of many analytical laboratories around the world. The current methods used in analysis are time-consuming, laborious, and expensive. A "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) method for analysis of pesticide residues in food was recently introduced to provide a much more efficient way to better meet laboratory needs. This study validates how the original QuEChERS method can efficiently provide excellent results for more than 200 pesticide residues in fruit and vegetable commodities. It is anticipated that this approach will be used by monitoring laboratories routinely in the future to replace the less efficient methods in current use.
Technical Abstract: Validation experiments were conducted of a simple, fast, and inexpensive method for the determination of 229 pesticides fortified at 10-100 ng/g in lettuce and orange matrices. The method is known as the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residues in foods. The procedure involved the extraction of 15 g sample with 15 mL acetonitrile, followed by a liquid-liquid partitioning step formed by adding 6 g anhydrous MgSO4 plus 1.5 g NaCl. After centrifugation, the extract was decanted into a tube containing 300 mg primary secondary amine (PSA) sorbent plus 1.8 g anhydrous MgSO4, which constituted a cleanup procedure called dispersive solid-phase extraction (dispersive-SPE). After a second shaking and centrifugation step, the extract was then transferred to autosampler vials for concurrent analysis by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS-MS). Each analytical method was designed to analyze 144 pesticides with 59 targeted by both instruments. Recoveries for all but 11 of the analytes in at least one of the matrices were between 70-120% (90-110% for 206 pesticides), and repeatabilities typically <10% were achieved for a wide range of fortified pesticides, including methamidophos, spinosad, imidacloprid, and imazalil. Dispersive-SPE with PSA retained carboxylic acids (e.g. daminozide), and <50% recoveries were obtained for asulam, pyridate, dicofol, thiram, and chlorothalonil. Many actual samples and proficiency test samples were analyzed by the method, and the results compared favorably with those from traditional methods.