Publication | Open Access
Validation of a Fast and Easy Method for the Determination of Residues from 229 Pesticides in Fruits and Vegetables Using Gas and Liquid Chromatography and Mass Spectrometric Detection
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2005
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QuEChERS is a widely used, quick, easy, cheap, effective, rugged, and safe approach for extracting pesticide residues from foods. The study aimed to validate a rapid, inexpensive method for quantifying 229 pesticides in lettuce and orange at 10–100 ng g⁻¹. Samples were extracted with acetonitrile, partitioned with MgSO₄/NaCl, cleaned by dispersive SPE with PSA, and analyzed by GC‑MS (ion trap) and LC‑MS/MS (triple quadrupole) targeting 144 pesticides, 59 of which were common to both instruments. The method achieved 70–120 % recoveries (90–110 % for 206 pesticides) with <10 % repeatability, and performed comparably to conventional techniques on real and proficiency samples, though carboxylic acids suffered <50 % recoveries.
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 matrixes. 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 a 15 g sample with 15 mL acetonitrile, followed by a liquid–liquid partitioning step performed 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 acetonitrile extract was transferred to autosampler vials for concurrent analysis by gas chromatography/mass spectrometry with an ion trap instrument and liquid chromatography/tandem mass spectrometry with a triple quadrupole instrument using electrospray ionization. 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 matrixes were between 70–120% (90–110% for 206 pesticides), and repeatabilities typically &lt;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 &lt;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.