SiREM’s webinar series features guest speakers who are subject matter experts to provide the latest information on technology advances in environmental remediation and site characterization. The webinars will combine recent research and development activities for new and emerging contaminants and technologies with real word applications to characterize and remediate contaminated sites.
We hope you will join us for our next webinar:
Dr. Tadeusz Górecki (Professor, University of Waterloo) will discuss passive sampling for assessing contaminant concentrations in indoor air, outdoor air and soil gas. Passive sampling is an attractive alternative to active sampling with Summa canisters or pumped ATD tubes – it is generally simpler and less expensive to deploy passive samplers on a large scale. A permeation passive sampler equipped with a polydimethylsiloxane (PDMS) membrane has been developed at the University of Waterloo and is available commercially from SiREM under the name Waterloo Membrane Sampler (WMS). The suitability of the WMS for compound-specific isotope analysis (CSIA) will also be discussed. A recently developed mathematical model allows prediction of the uptake rate and its changes during sampling based on the properties of the analyte and the sorbent. The model provides a valuable tool to assess changes in the uptake rate during sampling, to assign suitable exposure times at different analyte concentration levels, and to optimize the dimensions of the sampler in a manner that minimizes these changes during the sampling period.
Hester Groenevelt will present case studies where the WMS sampler was used for analysis of indoor and outdoor air and soil gas.
Passive sampling is based on free flow of analyte molecules from the sampled medium to a collecting medium due to a difference in chemical potential of the analyte between the two media. It is generally simpler and less expensive to deploy on a large scale compared to active sampling. Passive samplers can operate in the kinetic region, in which case the amount of analyte collected is proportional to its time-weighted concentration in the sampled medium, or in the equilibrium region, in which the amount collected is proportional to the analyte concentration around the time of sampler retrieval. Kinetic samplers require a well-defined uptake rate-limiting barrier for the results to be quantitative. When the barrier is made of a semi-permeable material (e.g., polydimethylsiloxane
A permeation passive sampler equipped with a PDMS membrane has been developed at the University of Waterloo and is available commercially from SiREM Labs under the name Waterloo Membrane Sampler (WMS). It uses mostly off-the-shelf components, which makes it simple and inexpensive. The sampler has been tested in numerous applications including analysis of indoor and outdoor air, soil gas, water and soil. The suitability of the WMS for compound-specific isotope analysis (CSIA) was also examined. A recently developed mathematical model allows prediction of the uptake rate and its changes during sampling based on the properties of the analyte and the sorbent. A gradual decline in the uptake rate during the sampling process is predicted, which is more pronounced when sampling higher concentrations. Decline of the uptake rate can be attributed to diminishing analyte concentration gradient within the membrane, which results from resistance to mass transfer and the development of analyte concentration gradients within the sorbent bed. The effects of changing the sampler dimensions on the rate of this decline in the uptake rate can be predicted from the model. Performance of the model was evaluated experimentally for sampling of toluene vapors under controlled conditions. The model predictions proved close to the experimental values. The model provides a valuable tool to predict changes in the uptake rate during sampling, to assign suitable exposure times at different analyte concentration levels, and to optimize the dimensions of the sampler in a manner that minimizes these changes during the sampling period.
Professor Tadeusz Górecki, Ph.D., Department of Chemistry, University of Waterloo
Tadeusz Górecki is a professor at the Department of Chemistry, University of Waterloo (ON). He obtained his M.Sc. Engineer (1981) and Ph.D. (1986) degrees from the Gdansk University of Technology, Poland, and the Professor of Chemical Sciences degree (2009) from the President of the Republic of Poland. Prof. Górecki’s main scientific interest is separation science, with a particular focus on passive sampling, comprehensive two‐dimensional gas chromatography (GCxGC), HPLC, and environmental analysis. He is the author/co‐author of 24 books/book chapters, over 160 papers published in peer reviewed journals, nearly 290 conference presentations (including 66 invited presentations) and 6 patents. His papers have been cited over 5000 times.
Hester Groenevelt, M.Sc., SiREM.
Hester Groenevelt has over 17 years of experience in environmental consulting, specializing in passive sampling and other sampling and analytical techniques. Hester holds a Masters of Science and a Bachelor’s of Environmental Studies from the University of Waterloo. At SiREM, her responsibilities include management of WMS services, including providing technical advice on the use and interpretation of the WMS samplers and results.
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