Conclusion
In this study, we have applied, for the first time, dissociation extraction in a water-free medium as a sample treatment strategy for high-effective complete extraction of pesticide residues of conazole group class from rapeseed oil. The proposed methodology was combined with gas chromatography with electron capture detection for quantitation of pesticide residues at limits of quantitation ranged from 3.0 to 300 μg kg−1. The obtained detection limits are below the maximum residue levels (MRLs) set by the European Union for the majority of pesticides. Dissociation extraction offers various attractive advantages compared with ordinary solvent extraction. It provides remarkably higher recoveries while using the same amount of extractant or allows consuming much less volume of solvent to achieve the same recoveries of azole pesticides. The clean-up procedure by hexane from acidified water–acetonitrile mixture with following neutralization and purification step with aqueous solution of dipotassium hydrogen orthophosphate provides removing of acids and hydrophilic substances from extract. The application of this sample preparation strategy, undoubtedly, could be extended to other kinds of vegetable oils and other pesticides with basic properties.