Rapid Multi-Residue Determination of Pesticides in Animal-Derived Food via Modified QuEChERS Sample Preparation and GC/MS

Abstract

A group of methods were developed for the determination of etofenprox, kresoxim-methyl, cyprodinil, azoxystrobin, and pyrimethanil residues in animal-derived food (milk, egg, pig liver, pig fat, pork, and chicken) by using QuEChERS (quick, easy, cheap, effective, rugged, and safe)-gas chromatography/mass spectrometry (GC/MS). With acetonitrile as the extraction solvent, the samples were pretreated with the improved QuEChERS method including extraction, salting-out, and purification processes. Then, all the sample extracts were analyzed with GC/MS in selected-ion monitoring (SIM) mode and quantified by the external standard method using the matrix-matched standard method. Under electron ionization conditions, the analysis was carried out with a DB-5 MS capillary column (30 m × 0.25 mm, 0.25 μm) at a flow rate of 2.0 mL min−1. 163, 116, 224, 344, and 198 were selected as quantitative ion of etofenprox, kresoxim-methyl, cyprodinil, azoxystrobin, and pyrimethanil, respectively. Under the optimal conditions, the calibration curves showed good linearity in the range of 0.0002–5.0 mg L−1 for the five pesticides mentioned above, with correlation coefficients (R2) were more than 0.99. The average recoveries of the five pesticides spiked at three levels were 72.46–104.88%, with the RSDs (n = 5) of 0.70–11.26%. The LODs (S/N > 3) of five pesticides were 0.0002–0.02 mg L−1; the LOQs were 0.0002–0.01 mg kg−1 in milk, egg, pig liver, pig fat, pork, and chicken samples. Such methods showed the advantages of simplicity, rapidness, and sensitivity, and could meet the requirements for the determination of five pesticides residues in various animal derived foods.