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Benzo(a)pyrene (B(a)p) is one kind of polycyclic aromatic hydrocarbons (PAHs), which is the most toxic compound, and has been used as a marker for the occurrence and effect of carcinogenic PAHs in edible oil. Due to its lipophicity, edible oil can be easily contaminated from the process like drying, leaching, roasting and home preparation.This paper focused on the deficiency of analyzing the trace PAHs in edible oil, and studied the concentration of B(a)p in edible oil and frying oil. Using environmental friendly reagent, DMC, for sample pretreatment, combined with ultrasound assisted extraction, solid phase extraction for purification and gas chromatography-mass spectrometry technique for detection.In this paper, green solvent DMC and ACN used as mix-extractant combined with ultrasound assisted liquid-liquid extraction was studied. The optimum method was achieved:CAN-DMC(3:2, V/V) as extractant, dosage of extractant25mL(15+10mL), ultrasonic power300W, ultrasonic temperature20℃and15min·time-1,extraction twice. The optimum method of solid phase extraction:alumina column was chosen as its strong adsorption,4mL of cycle-hexane was used as mobile phase,12mL of cycle-hexane as eluent and the later2～10mL of elution was collected for enrichment. After the pretreatment and purification process, the recovery was higher than95%and the RSD was less than9%, which met the requirements of trace analysis.The Agilent6890gas chromatography equipped with5975mass selective detector was used.1μL of sample solution was injected in the no-split mode onto a DB-5ms column. Helium carrier gas constant flow1.0mL·min-1; temperature:injector255℃, oven programme80℃for1min, rate22.5℃·min-1to200℃, rate10℃·min-1to260℃, rate5℃·min-1to final290℃, hold for10min, transfer line280℃. MS conditions:electron impact positive mode, detection SIM. The limit of detection (LOD)and the limit of quantification (LOQ) for B(a)p were established on the basis on the results of the recovery tested of the B(a)p standard solution. The LOQ of this method was0.017μg·L-1and the LOD was0.052μg·L-1.
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