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Uptake rate behavior of tube-type passive samplers for volatile organic compounds under controlled atmospheric conditions
Abstract A systematic laboratory research was performed to investigate the diffusive uptake of four target compounds (limonene, toluene, ethyl acetate, hexane) on axial-sampling sorbent tubes filled with Tenax TA. In a controlled atmosphere (temperature: 21.0 ± 1.8 °C; relative humidity set at different values between 5 and 80%), these passive samplers were exposed for 1, 3 and 7 days to a constant target compound concentration between 8 and 85 ppbv. Simultaneous active sampling and TD-GC-MS analysis was performed to determine VOCs concentrations. A power-law relationship between the sorbed mass on the sampler and exposure dose (11–179 ppmv min) was observed for all compounds. Compounds with a lower Tenax to air partitioning coefficient, i.e. with a lower affinity for Tenax showed a larger deviation from the expected linear relationship, assuming theoretical sampling rates on an ideal sorbent. Results showed that experimentally determined uptake rates (0.90–2.12 ng (ppmv min)−1) may be up to a factor of 2 lower than the theoretical ideal sampling rates, calculated from the molecular diffusion coefficients and the geometrical parameters of the sampler. The applicability of internal standard calibration for passive sampling was evaluated and a practical methodology is proposed with ethylbenzene-d10 as an internal standard.
Highlights ► Four air pollutants are studied: limonene, toluene, ethyl acetate and hexane. ► The diffusive uptake process is studied quantitatively and mechanistically. ► Sampling dose and thermodynamic sorption constants affect the uptake behavior. ► Ideal uptake rates underestimate TWA concentrations for Tenax TA-filled samplers. ► A method is proposed to apply internal standard calibration for passive sampling.
Uptake rate behavior of tube-type passive samplers for volatile organic compounds under controlled atmospheric conditions
Abstract A systematic laboratory research was performed to investigate the diffusive uptake of four target compounds (limonene, toluene, ethyl acetate, hexane) on axial-sampling sorbent tubes filled with Tenax TA. In a controlled atmosphere (temperature: 21.0 ± 1.8 °C; relative humidity set at different values between 5 and 80%), these passive samplers were exposed for 1, 3 and 7 days to a constant target compound concentration between 8 and 85 ppbv. Simultaneous active sampling and TD-GC-MS analysis was performed to determine VOCs concentrations. A power-law relationship between the sorbed mass on the sampler and exposure dose (11–179 ppmv min) was observed for all compounds. Compounds with a lower Tenax to air partitioning coefficient, i.e. with a lower affinity for Tenax showed a larger deviation from the expected linear relationship, assuming theoretical sampling rates on an ideal sorbent. Results showed that experimentally determined uptake rates (0.90–2.12 ng (ppmv min)−1) may be up to a factor of 2 lower than the theoretical ideal sampling rates, calculated from the molecular diffusion coefficients and the geometrical parameters of the sampler. The applicability of internal standard calibration for passive sampling was evaluated and a practical methodology is proposed with ethylbenzene-d10 as an internal standard.
Highlights ► Four air pollutants are studied: limonene, toluene, ethyl acetate and hexane. ► The diffusive uptake process is studied quantitatively and mechanistically. ► Sampling dose and thermodynamic sorption constants affect the uptake behavior. ► Ideal uptake rates underestimate TWA concentrations for Tenax TA-filled samplers. ► A method is proposed to apply internal standard calibration for passive sampling.
Uptake rate behavior of tube-type passive samplers for volatile organic compounds under controlled atmospheric conditions
Walgraeve, Christophe (author) / Demeestere, Kristof (author) / Dewulf, Jo (author) / Van Huffel, Katrijn (author) / Van Langenhove, Herman (author)
Atmospheric Environment ; 45 ; 5872-5879
2011-06-24
8 pages
Article (Journal)
Electronic Resource
English
Spatial analysis of volatile organic compounds in South Philadelphia using passive samplers
| Taylor & Francis Verlag | 2016