Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/27/2010
Publication Date: 5/26/2010
Citation: Koesukwiwat, U., Lehotay, S.J., Mastovska, K., Dorweiler, K.J., Leepitpatpiboon, N. 2010. Extension of the QuEChERS Method for Pesticide Residues in Cereals to Flaxseeds, Peanuts, and Doughs. Journal of Agricultural and Food Chemistry. 58:5950-5958. Interpretive Summary: The analysis of pesticide residues in food products is an important food safety function of countless regulatory and private laboratories worldwide. High quality results are needed in the analyses to protect the consumer, meet regulations, and ensure good environmental practices by farmers, and yet the methods must be fast, inexpensive, easy, and safe to perform. We developed the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method for pesticide residue analysis previously, and this paper describes how it can be modified to analyze pesticide residues in fatty foods, such as flaxseeds, doughs, and peanuts. The method was shown to be acceptable for routine monitoring purposes, and it was implemented in General Mills for their food quality control purposes. Other laboratories will also likely use this approach worldwide to save costs of analysis while still achieving high quality results.
Technical Abstract: A simple method was evaluated for the determination of pesticide residues in flaxseeds, doughs, and peanuts using gas chromatography-time-of-flight mass spectrometry (GC-TOF) for analysis. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, which was previously optimized for cereal grain samples, was evaluated in the fatty matrices. This extraction method involves first mixing the sample with 1/1 water/acetonitrile for an hour to swell the matrix and permit the salt-out liquid-liquid partitioning step using anh. MgSO4 and NaCl. After shaking and centrifugation, cleanup is done by dispersive-solid phase extraction (d-SPE) using 150 mg anh. MgSO4, 150 mg PSA, and 50 mg C-18 per mL extract. This method gave efficient separation of pesticides from fat and removal of co-extracted substances better than gel permeation chromatography or use of a freeze-out step, which involved excessive use of solvent and/or time. The optimized analytical conditions were evaluated in terms of recoveries, reproducibilities, limits of detection, and matrix effects for 34 representative pesticides using different types of flaxseeds, peanuts, and doughs. Use of matrix-matched standards provided acceptable results for most pesticides with overall average recoveries between 70-120% and consistent RSDs <20% for semi-polar pesticides and <26% for lipophilic pesticides typically over the course of multiple days.