Determination of 14 Lipophilic Pesticide Residues in Raw Propolis by Selective Sample Preparation and Gas Chromatography–Tandem Mass Spectrometry

A selective and reliable method was developed and validated for the determination of 14 lipophilic pesticides in raw propolis by gas chromatography–tandem mass spectrometry (GC-MS/MS) analysis. A test portion of milled sample was extracted with n-hexane followed by back extraction with acetonitrile and cleanup using EMR-Lipid and Florisil column adsorption. Matrix-matched standards were used to compensate for matrix effects. Typical linear correlation coefficients (R2) were ≥ 0.989 in concentration range of 0.001–0.200 μg/mL. Method validation was carried out at three spiking levels and three individual days, and it was found that the mean interday average recoveries were 61.0–106.8% with relative standard deviations ≤ 16.9%. Limits of quantification were ranged from 0.002 to 0.020 μg/g. Analysis of market propolis samples showed contamination by pesticides (e.g., tau-fluvalinate) to some degree.