Citation:

Wallace, M., J. Pleil, D. Whitaker, AND K. Oliver. Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry. JOURNAL OF CHROMATOGRAPHY A. Elsevier Science Ltd, New York, NY, 1602:19-29, (2019). https://doi.org/10.1016/j.chroma.2019.05.030

Impact/Purpose:

PAHs are prevalent environmental contaminants and pose a myriad of health risks upon exposure. PAHs have not been extensively analyzed using sorbent tube technology, but gas-phase sampling coupled with thermal desorption (TD)- gas chromatography/mass spectrometry (GC-MS) analysis is an attractive method for assessing these compounds in breath and gas-phase environmental samples. However, initial studies of PAHs sampling using sorbent tubes revealed poor recovery of PAHs from Carbograph 1TD/2TD sorbent tubes. The reasons for poor recovery of PAHs from these tubes was investigated. This research describes methods for polycyclic aromatic hydrocarbon (PAH) sampling using sorbent tube technology. In this study, a variety of sorbent tubes were tested for performance in sampling and analysis of eight PAHs, looking at percent recovery and reactivity of the PAHs with sorbent materials. The type of sorbent tube selected for PAH analysis as well as the method parameters for standard loading and thermal desorption were found to affect PAH recovery and reactivity. Ultimately, carbograph sorbents paired with stainless steel tubes were found to contribute the most to observed PAH reaction products. This study is significant for further TD method development and analysis of PAHs. Researchers will be able to use these results to select sorbent tubes for PAH analysis and avoid using types of sorbent tubes that are known to be problematic for PAH collection, desorption, and reactivity. These results will be of interest to researchers studying PAHs using TD-GC-MS within EPA as well as in other federal agencies.

Description:

This article describes the optimization of methodology for extending the measurement of volatile organic compounds (VOCs) to increasingly heavier polycyclic aromatic hydrocarbons (PAHs) with a detailed focus on recent sorbent tube technology. Although PAHs have lower volatility than compounds such as benzene, toluene, ethylbenzene and xylenes, these semi-volatile compounds can be detected in air and breath samples. For this work, PAHs were captured on sorbent tubes and subsequently analyzed using automated thermal desorption gas chromatography – mass spectrometry (ATD-GC/MS). While many different sorbent tubes are commercially available, optimization for airborne PAH sampling using sorbent tubes has not been previously considered. Herein, several commercially available sorbent tubes, including Carbograph 2 TD/1TD, Tenax TA, XRO-440, and inert-coated PAH tubes are compared to determine the relative recovery for eight PAHs commonly found in the environment. Certain types of sorbent materials were found to be better suited for PAH recovery during thermal desorption, and PAH reaction products were observed on several types of sorbent tubes, including graphitized carbon black sorbents with stainless steel tube materials. As such, selection of sorbent tube media should be carefully considered prior to embarking on a PAH study.

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