Method Validation for Imidacloprid and Dimethoate Residues in Apples by QuEChERS and LC–MS/MS Analysis

All methods used for pesticide residue analysis must be validated prior to implementation of original laboratory samples analysis.This study performed to validate analytical procedure for imidacloprid ve dimethoate residues in apples. For this aim, untreated blank Golden Delicious and Starking Delicious samples were homogenized and fortified at 3 levels with pesticides. 10 g of apples were subjected to QuEChERS extraction and cleanup procedure. Pesticide analysis performed with LC-MS/MS. Since matrix effect was important for both pesticides and both apple varieties, matrix matched calibration (MC) was used for quantification. Method validation was carried out by performance parameters such as, recovery, method detection limit, repeatability, precision. All parameters figures were within the required limits. For imidacloprid and dimethoate analytes, recoveries (n=150) averaged 88.34% (RSD 7.72%), for two apple commodites over the validation range. For overall recovery of the analytical procedure was 89.50%(RSD12.02% ). These values were compatible with the required figure for recovery (70–120%) and repeatability (RSD ≤ 20%). Method detection limits of analytes were below the EU MRLs and also TGK MRLs. Calibration curve of two compound were linear with the 5–200 ng/mLrange.