Method optimization, validation and assessment of pesticide residues in table grapes marketed in Islamabad, Pakistan

Abstract Two different strategies QuEChERS AOAC 2007.01 and QuEChERS EU-15662 for the extraction of pesticide residues from grapes were compared. The QuEChERS EU-15662 method demonstrated optimal recoveries for 21 pesticides during the extraction step. For the clean-up process, florisil, PSA, and activated charcoal were compared using d-SPE. Among these sorbents, PSA exhibited the most favorable recoveries. The method validation results indicates recoveries for the majority of the studied pesticides fell within the acceptable range of 70–120%, with % RSD values consistently below 20%. The LOD for various pesticides ranged from 0.027 to 0.09 mg/kg, while the LOQ ranged from 0.085 to 0.21 mg/kg. Matrix effect was less than 20% for all the studied pesticides. The validated method was applied to analyze sixteen samples collected from the local fruit market. Four (25%) samples were found to be contaminated with imidacloprid, acetamiprid, and tebuconazole. Traces of thiacloprid, azoxystrobin, and hexaconazole were also detected in these four positive samples. However, in all samples, the identified residues were below the MRLs prescribed by the EU.