Analysing organochlorine pesticides in strawberry jams using GC-ECD, GC-MS/MS and QuEChERS sample preparation

Abstract

This paper describes a comparison of adaptations of the QuEChERS (quick, easy, cheap, effective, rugged and safe) approach for the determination of 14 organochlorine pesticide (OCP) residues in strawberry jam by concurrent use of gas chromatography (GC) coupled to electron capture detector (ECD) and GC tandem mass spectrometry (GC-MS/MS). Three versions were tested based on the original QuEChERS method. The results were good (overall average of 89% recoveries with 15% RSD) using the ultrasonic bath at five spiked levels. Performance characteristics, such as accuracy, precision, linear range, limits of detection (LOD) and quantification (LOQ), were determined for each pesticide. LOD ranged from 0.8 to 8.9 µg kg⁻¹; LOQ was in the range of 2.5–29.8 µg kg⁻¹; and calibration curves were linear (r ²> 0.9970) in the whole range of the explored concentrations (5–100 µg kg⁻¹). The LODs of these pesticides were much lower than the maximum residue levels (MRLs) allowed in Europe for strawberries. The method was successfully applied to the quantification of OCP in commercially available jams. The OCPs were detected lower than the LOD.

Keywords:

• chromatography – GC
• extraction
• GC/MS
• pesticides – organochlorine
• pesticide residues
• processed foods
• organic foods
• cooked foods
• fruit

Acknowledgements

This research was supported by a PhD grant from the FCT (Fundação para a Ciência e a Tecnologia – BD/47200/2008) and Grant Number PEst-C/EQB/LA0006/2011.