Evalualtion of the QuEChERS sample preparation approach for the analysis of pesticide residues in olives

Authors: CUNHA, SARA - UNIVERSIDADE DO PORTO; Lehotay, Steven; Mastovska, Katerina; FERNANDES, JOSE - UNIVERSIDADE DO PORTO; OLIVEIRA, M. BEATRIZ - UNIVERSIDADE DO PORTO

Submitted to: Journal of Separation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2006
Publication Date: 2/10/2007
Citation: Cunha, S., Lehotay, S.J., Mastovska, K., Fernandes, J.O., Oliveira, M.P. 2007. Evalualtion of the QuEChERS sample preparation approach for the analysis of pesticide residues in olives. Journal of Separation Science. 30:620-632.

Interpretive Summary: Olives and olive oil are important commodities for nutritional health benefits, and they constitute critical trade commodities that contribute to the economies of Mediterranean countries. Pesticide residues must be analyzed in olives and olive oil for food safety and regulatory purposes, but current methods of analysis are too slow, laborious, and wasteful. Better methods of analysis are needed, and this paper describes the novel application of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for multiclass, multiresidue analysis of pesticides in olives and olive oil. These are considered high fat matrices, which pose a challenge to the QuEChERS method. The problems with the high oil content were overcome by the use of direct sample introduction in gas chromatography, and additional cleanup of the extracts was also performed without additional time or expense. This method is likely to become the method of choice in residue analysis of olives and its oil, which should reduce the analytical cost burden for analysis by exporters and may improve food safety and trade of this important commodity.

Technical Abstract: This paper describes the use of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and cleanup of 15 pesticide residues of regulatory importance in olives and olive oil. These products contain a high lipid content, which can adversely affect pesticide recoveries and harm traditional chromatographic systems. For extraction, the main factors (oil and water content) were studied and optimized in experiments to maximize pesticide recoveries. Dispersive solid-phase extraction with different sorbents was also investigated to minimize matrix co-extractives and interferences. For analysis, a new automated direct sample introduction device was tested in GC-MS to avoid nonvolatile co-extractives from contaminating the instrument. LC-MS/MS with positive electrospray ionization was used for those pesticides that were difficult to detect by GC-MS. The final method was validated for olives in terms of recoveries, repeatabilities, and reproducibilities using both detection techniques. The results demonstrated that the method achieved acceptable quantitative recoveries of 70-109% with RSDs <20% for GC-MS and 88-130% with RSDs <10% for LC-MS/MS, and detection limits at or below the regulatory maximum residue limits for the pesticides were achieved.