Method Optimization, Validation, and Assessment of Pesticide Residues in Table Grapes Marketed in Islamabad, Pakistan

ABSTRACT Two Quick Easy Cheap Effective Rugged Safe (QuEChERS) extraction strategies, AOAC International and European Union Methods, were compared in terms of method accuracy and precision for pesticide residues analysis in grapes. The QuEChERS EU‐15662 method demonstrated optimal recoveries for 21 pesticides commonly used for grapes during the extraction step. For the cleanup process, florisil, primary secondary amine (PSA), and activated charcoal were compared using dispersive solid‐phase extraction. Among these sorbents, PSA exhibited the most satisfactory recoveries. The method validation results indicate recoveries for most of the studied pesticides fell within the acceptable range of 70%–120%, with % RSD values consistently below 20%. The limit of detection for various pesticides ranged from 0.027 to 0.09 mg/kg, whereas the limit of quantitation 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 16 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 the samples, the identified residues were below the maximum residue limits prescribed by the European Union.