A simple approach for pesticide residues determination in green vegetables based on QuEChERS and gas chromatography tandem mass spectrometry

Abstract

Preparing matrix-matched calibration curves for each matrix type makes multiresidue methods for pesticides determination in foods a labor-intensive endeavor. Herein, a highly efficient method for the purification of plant extracts (6 mL) based on QuEChERS, with 900 mg anhydrous MgSO4, 300 mg C18, 300 mg ChloroFiltr at d-SPE stage, combined with gas chromatography with tandem mass spectrometry for the determination of 164 pesticides in vegetables of varying chlorophyll content was developed. This method enables the application of a matrix-matched curve prepared in one type of matrix for the determination of pesticides in food samples with different chlorophyll contents. Method validation adhered to the requirements of SANTE/12682/2019 document (recoveries: 70–120%, RSD<20%, LOQ: 0.005 mg/kg, matrix effect: ± 20%, uncertainty<50%). The method was employed for pesticides determination in vegetables purchased from local markets. In 27 samples, pendimethalin was the most abundant compound determined (9 samples) in the concentration range of 0.007–0.065 mg/kg, followed by difenoconazole (5 samples) in the concentration range of 0.013–0.025 mg/kg. The highest concentration exceeding the maxium residual level was found for chlorpyrifos (0.110 mg/kg in dill) and for tebuconazole (0.009 mg/kg in Chinese cabbage). None of the samples examined revealed the simultaneous occurrence of more than three pesticides.

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