Determination of Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate: Collaborative Study
Authors: Lehotay, Steven J; Collaborators: Mary O'Neil; Jose Tully; Antonio Valverde Garca; Mariano Contreras; Hans Mol; Volkmar Heinke; Thomas Anspach; Gnter Lach; Richard Fussell; Katerina Mastovska; Mette Erecius Poulsen; Amy Brown; Walter Hammack; Jo Marie Cook; Lutz Alder; Karen Lindtner; Miguel GamnVila; Marvin Hopper; Andr de Kok; Maurice Hiemstra; Frank Schenck; Anthony Williams; Alesia Parker
Source: Journal of AOAC International, Volume 90, Number 2, March 2007 , pp. 485-520(36)
Publisher: AOAC International
Abstract:A collaborative study was conducted to determine multiple pesticide residues in fruits and vegetables using a quick, simple, inexpensive, and effective sample preparation method followed by concurrent analysis with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/ tandem mass spectrometry (LC/MS/MS). For short, the method is known as QuEChERS, which stands for quick, easy, cheap, effective, rugged, and safe. Twenty representative pesticides were fortified in 3 matrixes (grapes, lettuces, and oranges) at 3 duplicate levels unknown to the collaborators ranging from 10 to 1000 ng/g. Additionally, 8 incurred pesticide residues were determined. Thirteen laboratories from 7 countries provided results in the study, and a variety of different instruments were used by collaborators. The QuEChERS procedure simply entails 3 main steps: (1) a 15 g homogenized sample is weighed into a 50 mL centrifuge tube to which 15 mL acetonitrile containing 1 HOAc is added along with 6 g MgSO4 and 1.5 g NaOAc, and the tube is shaken and centrifuged; (2) a portion of the extract is mixed with 3 + 1 (w/w) MgSO4primary secondary amine sorbent (200 mg/mL extract) and centrifuged; and (3) the final extract is analyzed by GC/MS and LC/MS/MS. To detect residues <10 ng/g in GC/MS, large-volume injection of 8 L is typically needed, or the extract can be concentrated to 4 g/mL in toluene, in which case 2 L splitless injection is used. In the study, the averaged results for data from 713 laboratories (not using internal standardization) for the 18 blind duplicates at the 9 spiking levels in the 3 matrixes are as follows [%recovery and reproducibility relative standard deviation (RSDR, %)]: atrazine, 92 (18); azoxystrobin, 93 (15); bifenthrin, 90 (16); carbaryl, 96 (20); chlorothalonil, 70 (34); chlorpyrifos, 89 (25); cyprodinil, 89 (19); o, p-DDD, 89 (18); dichlorvos, 82 (21); endosulfan sulfate, 80 (27); imazalil, 77 (33); imidacloprid, 96 (16); linuron, 89 (19);methamidophos, 87 (17); methomyl, 96 (17); procymidone, 91 (20); pymetrozine, 69 (19); tebuconazole, 89 (15); tolylfluanid (in grapes and oranges), 68 (33); and trifluralin, 85 (20). For incurred pesticides, kresoxim-methyl (9.2 3.2 ng/g) and cyprodinil (112 18) were found in the grapes; permethrins (112 41), -cyhalothrin (58 11), and imidacloprid (12 2) were determined in the lettuces; and ethion (198 36), thiabendazole (53 8), and imazalil (13 4) were determined in the oranges. Chlorpyrifosmethyl (200 ng/g) was used as a quality control standard added during sample homogenization and yielded 86% recovery and 19% RSDR. Intralaboratory repeatabilities for the method averaged 9.8% RSD for all analytes. The results demonstrate that the method is fit-for- purpose to monitor many pesticide residues in fruits and vegetables, and the Study Director recommends that it be adopted Official First Action.
Document Type: Research Article
Affiliations: U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Ln, Wyndmoor, PA 19038.
Publication date: 2007-03-01
- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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- By this author: Lehotay, Steven J ; Collaborators: Mary O'Neil; Jose Tully; Antonio Valverde Garca; Mariano Contreras; Hans Mol; Volkmar Heinke; Thomas Anspach; Gnter Lach; Richard Fussell; Katerina Mastovska; Mette Erecius Poulsen; Amy Brown; Walter Hammack; Jo Marie Cook; Lutz Alder; Karen Lindtner; Miguel GamnVila; Marvin Hopper; Andr de Kok; Maurice Hiemstra; Frank Schenck; Anthony Williams; Alesia Parker