Comparison of Soxhlet and Ultrasonic Method for Extraction Polycyclic Aromatic Hydrocarbons in PM_2.5

Objectives To compare the soxhlet and ultrasonic methods for extraction of six polycyclic aromatic hydrocarbons(PAHs), including benzobfluoranthene, benzokfluoranthene, benzoapyrene, dibenza, hanthracene, indeno1, 2, 3-cdpyrene and benzoghiperylene in PM_2.5 in the air.

Methods Sample and blank filter membranes added with standards were extracted by soxhlet and ultrasonic method, respectively, and detected by HPLC-fluorescence detector. The relative standard deviation(RSD) and the recovery of standard addition were calculated.

Results The RSDs of six PAHs on blank filter membrane extracted by soxhlet and ultrasonic method were 3.6% and 2.9%, respectively. The recoveries of standard addition of six PAHs on blank filter membranes extracted by Soxhlet and ultrasonic method were 91.7% and 90.3%, respectively; those on sample filter membranes were 89.0% and 83.3%, respectively. The standard deviations of recoveries for 6 PAH_S on blank filter membranes extracted by soxhlet and ultrasonic method were 18.5% and 2.8%, respectively; those on sample filter membranes were 1.7% and 3.1%, respectively. The results of actual sample detected by these two methods were comparable.

Conclusions Many factors in the process of soxhlet extraction might affect the results because of its complex steps. Ultrasonic extraction method was simple and the results were relatively stable. Ultrasonic extraction was a simple, rapid and practicable preparation method for the detection of PAHs in PM_2.5.