Analysis of 140 pesticides from conventional farming foodstuff samples after extraction with the modified QuECheRS method

Abstract

Pesticides in foodstuff are becoming a major issue due to their intensive use in agriculture. Thus an appropriate control of their residues in food samples has to be operated. In this study we analysed 105 pesticides with GC/SQ-MS and 46 pesticides with HPLC/IT-MS after extraction with the QuECheRS method in four matrices (grape, lemon, onion and tomatoes). For GC-amenable substances, the LOD and LOQ ranged from 0.4 to 48.2mug/kg and from 1.2 to161mug/kg, respectively. For HPLC-amenable substances, they varied from 1.0 to 115mug/kg and from 3.3 to 382mug/kg, respectively. With GC/MS, 61-82% of the substances showed a recovery in the range of 70-110% and 6-30 % presented a recovery higher than 110% at the 500mug/kg fortification level. With HPLC/MS, 87-93% of the substances presented recoveries in the range of 70-110% at the 500mug/kg fortification level compared to 78-85% at the 50mug/kg fortification level. Lemon and onion showed poor recoveries but are known to be difficult matrices (high acidic and high sulfur content, respectively). The method was proved to be repeatable with RSD lower than 20% at 500mug/kg and lower than 15% at 50mug/kg with both devices.

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