Method validation, residue and risk assessment of 260 pesticides in some leafy vegetables using liquid chromatography coupled to tandem mass spectrometry.

In the present study, QuEChERS method was optimized and validated for determination of 260 pesticides by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method had a suitable linearity (R2 ≥ 0.99). Limit of detection (LOD) and limit of quantification (LOQ) were ranged from 0.56 to 2.99 µg kg-1 and 1.88 to 9.99 µg kg-1 respectively. Average recoveries varied from 71.14% to 118.83%. Repeatability conditions and intra-laboratory reproducibility conditions of the method expressed as %RSD were found between 0.55% and 16.69% and 0.74% to 19.06%, respectively. The method was used to detect pesticide residue levels of leafy vegetables collected from the open markets, greenhouses and wholesale vegetable market. The pesticide residues were detected in 57.6% of the all samples. In five samples, pesticide residues were above Maximum Residue Levels (MRLs). The risk assessment study for detected pesticides in samples indicated that leafy vegetables consumption was safe for consumers.