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Volume 11, No. 4, August 2011, Pages 387-392 PDF(266 KB)  
doi: 10.4209/aaqr.2011.01.0001   

Extraction of Gaseous VOCs Using Passive Needle Trap Samplers

Wen-Hsi Cheng1, Weiqiang Zhan2, Janusz Pawliszyn2

1 Department of Occupational Safety and Hygiene, Fooyin University, Kaohsiung 83102, Taiwan
2 Department of Chemistry, University of Waterloo, Waterloo, Ontario, N2L 3G1 Canada




Gaseous toluene, ethylbenzene and o-xylene (TEX) were extracted by using the divinylbenzene (DVB) particle of 60–80 mesh as a sorbent packed in series of needle trap samplers (NTS). The feasibility of using this self-designed DVB-NTS as a diffusive time-weighted average (TWA) sampler for occupational hygiene applications was evaluated by examining extended sampling periods of 4–12 hr. Additionally, the NTS was compared in terms of extraction efficiency by simultaneously using the 75 μm Carboxen/polydimethylsiloxane-solid phase microextration (Carboxen/PDMS-SPME) fiber for sampling TEX. Experimental results indicated that, regardless of static (in a bulb) or dynamic samplings (in a flowing gas stream), the packed DVB-NTS achieved higher TEX extraction rates (ng VOCs/min) than those of 75 μm Carboxen/PDMS-SPME fiber. The decreasing rates of extracting TEX for SPME fiber were 24–34% and 28–36% as NTS performed during the sampling periods of 240 and 480 min, respectively. Typically, the maximum VOC adsorption capacities per mg DVB were measured as 5.692 μg toluene, 7.669 μg ethylbenzene and 5.199 μg o-xylene. During the sampling period of 12 hr, the DVB-NTS extracted 1600–1800 ng of individual TEX components from a continuously flowing air stream, in which the gas flow rate equals 200 mL/min. We recommend the badgelike or penlike NTS as an alternative passive sampler to the legal active sampling method 1501, National Institute of Occupational Safety and Health (NIOSH), owing to its small size and high extraction capacity of TEX.



Keywords: Solid phase microextraction (SPME); Needle trap; Volatile organic compound (VOC); Time-weighted average (TWA) sampling; Occupational hygiene.



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