Evaluation of QuEChERS sample preparation and liquid chromatography-triple-quadrupole mass spectrometry method for the determination of 109 pesticide residues in tomatoes

A multiresidue method based on modified QuEChERS (quick, easy, cheap, effective, rugged and safe) sample preparation, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and validated for the determination of 109 selected multiclass pesticides in tomatoes. The recovery yields ranged from 77.1% to 113.2%, with repeatabilities of 4.4-19.2% and within-laboratory reproducibilities of 7.1-18.4%. The limit of detections (LODs) for target analytes in tomato extract were between 0.5 and 10.8 mu g kg(-1), and the limit of quantifications (LOQs) were between 1.3 and 30.4 mu g kg(-1). The expanded measurement uncertainty was not higher than 30% for all target analytes. The method has been successfully applied to the analysis of 345 tomato samples obtained from local markets and tomato traders. Residues of acetamiprid, azoxystrobin and triadimefon were identified and measured in 9.6% of tomato samples, ranging from 0.015 to 0.37 mg kg(-1). (C) 2014 Elsevier Ltd. All rights reserved.