Development and Application of a Needle Trap Device for Time-Weighted Average Diffusive Sampling

A simple, cost-effective analysis combining solventless extraction, thermal desorption, and determination of volatile organic compounds (VOCs) was developed and validated. A needle trap device (NTD) packed with the sorbent Carboxen1000 was used as a time-weighted average (TWA) diffusive sampler to c...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2008-10, Vol.80 (19), p.7275-7282
Main Authors: Gong, Ying, Eom, In-Yong, Lou, Da-Wei, Hein, Dietmar, Pawliszyn, Janusz
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemistry
Chromatographic methods and physical methods associated with chromatography
Diffusion
Exact sciences and technology
Gas chromatographic methods
General, instrumentation
Solution chemistry
Solvent extraction processes
Sorption
VOCs
Volatile organic compounds
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Summary:A simple, cost-effective analysis combining solventless extraction, thermal desorption, and determination of volatile organic compounds (VOCs) was developed and validated. A needle trap device (NTD) packed with the sorbent Carboxen1000 was used as a time-weighted average (TWA) diffusive sampler to collect target compounds by molecular diffusion and adsorption to the packed sorbent. This process can be described with derivations of Fick’s first law of diffusion, which expresses the relation between the TWA concentrations to which the passive sampler is exposed and the mass of analytes adsorbed to the packed sorbent in the sampler. The effects of experimental factors such as temperature, pressure, humidity, and face velocity were taken into account in applying diffusive sampling under nonideal conditions. This study demonstrates that NTD is effective for air analysis of benzene, toluene, ethylbenzene, and o-xylene (BTEX), due to the good adsorption/desorption quality of Carboxen 1000 and to the special geometric shape of the needle with a small cross section avoiding the need for calibration. Storage tests showed good storage stability for BTEX. Verification of the theoretical model showed good agreement between theoretical and experimental sampling rates. Method validation done against NIOSH method 1501, SPME, and NTD active sampling revealed good agreement between those methods. Automated NTD sample introduction to a gas chromatograph facilitates the use of this technology for industrial hygiene applications.
ISSN:0003-2700
1520-6882
DOI:10.1021/ac800884f