Determination of 33 Polychlorinated Biphenyls in the Atmosphere of Beijing Using Stir Bar Sorptive Extraction-Thermal Desorption Coupled with Gas Chromatography-Mass Spectrometry
A method was developed for the determination of Polychlorinated biphenyls(PCBs)in air by stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry(SBSE-TD-GC-MS)using polydimethylsiloxane(PDMS)-coated stir bar for passive air sampler.The optimized conditions for desorption temperature,desorption time and cryofocusing temperature were found to be 280℃,6 min and-40℃,respectively,along with the carry-over of up to 7%for 33 PCB congeners.Linearity,precision and repeatability of the method were investigated.The proposed method showed excellent linearities for 33 PCB congeners,with the correlation coefficients(r)>0.998 for 5 point calibrations.Better precision,intra-day repeatability and inter-day repeatability were obtained with RSDs(relative standard deviation)in the ranges of 0.79%-20.2%(n= 8),0.43%-29.8%(n=10)and 3.20%-29.6%(n = 20),respectively.Detection limits ranged from 0.01 to 2.51 pg,and the average recovery was 98%±18%.The developed method was applied to monitor PCBs in the atmosphere of Beijing.Eight PCB congeners were detected and the contents were in the range of 2.94-129 pg.PCB-52,PCB-123 and PCB-155 were always in the linear uptake phase,whereas PCB-1 and PCB-3 experienced linear uptake phase,curvilinear uptake phase and equilibrium phase during the sampling campaign of 32 days.The results indicated that SBSE-TD-GC-MS could be employed for sampling and quick determination of PCBs in atmosphere.
stir bar sorptive extractionthermal desorptionpolychlorinated biphenylspassive air sampling
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