Evaluation of Two Fast and Easy Methods for Pesticide Residue Analysis in Fatty Food Matrixes

Abstract

Two rapid methods of sample preparation and analysis of fatty foods (e.g., milk, eggs, and avocado) were evaluated and compared for 32 pesticide residues representing a wide range of physicochemical properties. One method, dubbed the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticide residue analysis, entailed extraction of 15 g sample with 15 mL acetonitrile (MeCN) containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 1 mL of the buffered MeCN extract underwent a cleanup step (in a technique known as dispersive solid-phase extraction) using 50 mg each of C18 and primary secondary amine sorbents plus 150 mg MgSO4. The second method incorporated a form of matrix solid-phase dispersion (MSPD), in which 0.5 g sample plus 2 g C18 and 2 g anhydrous sodium sulfate was mixed in a mortar and pestle and added above a 2 g Florisil column on a vacuum manifold. Then, 5 × 2 mL MeCN was used to elute the pesticide analytes from the sample into a collection tube, and the extract was concentrated to 0.5 mL by evaporation. Extracts in both methods were analyzed concurrently by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. The recoveries of semi-polar and polar pesticides were typically 100% in both methods (except that basic pesticides, such as thiabendazole and imazalil, were not recovered in the MSPD method), but recovery of nonpolar pesticides decreased as fat content of the sample increased. This trend was more pronounced in the QuEChERS method, in which case the most lipophilic analyte tested, hexachlorobenzene, gave 27 ± 1% recovery (n = 6) in avocado (15% fat) with a <10 ng/g limit of quantitation.

Simple and fast analysis of tetrabromobisphenol A, hexabromocyclododecane isomers, and polybrominated diphenyl ethers in serum using solid‐phase extraction or QuEChERS extraction followed by tandem mass spectrometry coupled to HPLC and GC

“…Our results agreed with Lehotay's finding that C 18 removes only the most hydrophobic coextractants (e.g. lipids) and the recovery of the analytes is not affected [18]. Thus, C 18 was chosen in the clean-up step.…”

Determination of pesticide residues in olive oils with protected geographical indication or designation of origin

“…As it has been reported, high fatty matrices and, especially, olive oil (100% lipids) containing a high lipid content can adversely affect pesticide recoveries (Lehotay et al, 2005;Cunha et al, 2007;Koesukwiwat et al, 2010). For this purpose, the removal of macromolecular mass lipids from the extracts prior to GC analysis is necessary.…”

Comparison of different cleanup procedures for oil crops based on the development of a trace analytical method for the determination of pyraclostrobin and epoxiconazole

“…In the freeze-out step, the sedimentation effect when the lipids were kept at -20ЊC for 12 h was satisfactory [11]. In the dSPE procedure, PSA is a WAX sorbent that removes fatty acids from the extracts [26], and C 18 is a nonpolar sorbent that removes trace amounts of lipids from the extracts more effectively [27]. In the GPC method, most lipids have a molecular mass from 600 to 1500 [28], which is larger than that of pyraclostrobin (387.82) and epoxiconazole (329.76).…”