Determination of Polycyclic Aromatic Hydrocarbons in Edible Oil Using Fast and Sensitive Microwave-assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

Abstract

Edible oils as important fat-rich samples have the most probability in forming of polycyclic aromatic hydrocarbons. In this research an efficient, sensitive and fast microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by gas chromatography-mass spectrometry (GC-MS) was employed for isolation and determination of PAHs in edible oil. Effective parameters for extraction procedure including type and volume of extraction and disperser solvent, microwave time, NaCl amount and pH were optimized using response surface methodology (RSM) based on central composite design (CCD). In microwave procedure, PAHs extracted from oil sample with acetonitrile/acetone (50:50) and methanolic KOH in two steps. In microextraction stage, mixture of ethanol (disperser solvent), tetrachloroethylene (extraction solvent) and biphenyl (internal standard) was rapidly injected into the sample solution. After performing phase separation, sedimented phase was analyzed by GC-MS. For proposed method, the calibration curve was obtained in the range of 2–500 ng mL−1 with correlation coefficient (R2) 0.9346 to 0.9978. Enrichment factors were between 81 and 124 for PAHs and repeatability as relative standard deviations (RSDs) were 5.2% to 9.1% for all PAH compounds at a concentration of 10 ng mL−1. Limits of detection (LODs) and limits of quantitation (LOQs) were obtained in the range of 0.2–2.7 ng mL−1 and 0.6–9.1 ng mL−1, respectively. Comparison of this method with other analytical method showed that MAE-DLLME coupled with GC-MS is a powerful method for detecting PAHs in complex matrices. The validated method was applied for the determination of PAHs in real edible oil samples and acceptable results were obtained.