Emulsification/demulsification method coupled to GC-MS/MS for analysis of multiclass pesticide residues in edible oils.

A simple, rapid, and sensitive method was developed for simultaneous determination of 103 multiclass pesticides in edible oils. A new strategy of sample preparation involving a spontaneous emulsification followed by membrane-based demulsification was proposed. The developed strategy was compared with other reputed clean-up procedures and found to improve the removal efficiency of matrix interferences without a significant loss of pesticides. GC-MS/MS was used to evaluate the proposed treatment methodologies. Recovery studies were performed at 10, 20, and 50 μg/kg levels in soybean oil, olive oil, and rapeseed oil. Throughout the validations, 70-120% overall recoveries were achieved with RSDs < 10% for the majority of pesticides. Limits of quantification ranged from 10 to 50 μg/kg (10 μg/kg for over 92% pesticides), less than the regulatory MRLs. Twenty-two of 30 market samples were found to contain one or several detectable pesticide residues ranged from < 1 to 105.9 μg/kg.