Various parameters affecting the pesticide residues extraction efficiency from the plant materialWpływ różnych czynników na efektywność ekstrakcji pozostałości środków ochrony roślin z materiału roślinnego

Abstract

Summary In this study we introduced modifications of QuEChERS (Quick Easy Cheap Effective Rugged and Safe) method in terms of type of solvent (acetone, acetonitrile, ethyl acetate, dichloromethane), extraction temperature (25°C, 6°C, –18°C), extraction time (1–30 minutes) and way of extracting (by hand and using Heidolph Multi Reax shaker). The aim of the experiment was to investigate the influence of modifications on the pesticide residues extraction efficiency from the plant material. A mixture of 33 pesticides was quantitatively recovered from spiked tomato samples and determined using gas chromatography with nitrogen phosphorus detector and electron capture detector (GC–NPD/ECD). For each condition there were three replicates. Extraction by acetonitrile, ethyl acetate and dichloromethane gave good results (recoveries above 70% for almost all compounds). Ethyl acetate and dichloromethane were found to be more suitable solvents for QuEChERS extraction than acetonitrile. However, use of dichloromethane and ethyl acetate resulted in larger impact of interfering compounds than use of acetone and acetonitrile. In the presence of acetone recoveries of most compounds were below 70%. Shaking time and intensity were less important in condition of chilled and frozen samples (recoveries above 80%). Storage at room temperature and shaking with Heidolph decreased extraction efficiency with the length of shaking. 1 minute shaking by hand and 5 minutes shaking using Heidolph seemed sufficient for more than 70% yields under all temperature conditions.