Illustration of how the Waterloo Membrane Sampler works

Waterloo Membrane Sampler

The Waterloo Membrane Sampler (WMS) is used for passively measuring concentrations of volatile organic compounds (VOCs) in the subsurface and sewers.

The unique design of the WMS and regulatory acceptance of passive sampling for vapor intrusion mean that WMS is particularly well suited for measuring concentrations of volatile organic compounds (VOCs) in the subsurface and sewers. In addition, when compared to traditional methods, WMS is less expensive, easier to deploy, and provides results that are more representative of concentrations over time.

The WMS design incorporates a polydimethylsiloxane (PDMS) membrane across the face of a vial filled with a sorbent medium. VOC vapors distribute themselves into and permeate through the membrane at known and predictable rates. The sorbent traps the vapors, and the mass of each compound is determined. Thus, the WMS can be used to measure time-weighted average concentrations for virtually any VOC.

With traditional passive samplers, when water-vapor concentrations are high, sorbent can become saturated, preventing target analytes from sorbing leading to low-bias measurements —this often happens when sampling soil and sewer gas.

WMS-VP in a Vapor pin capsule
An example of the WMS-VP in a Vapor Pin® capsule for measuring VOC vapor concentrations in sub-slab areas.

Advantages of passive sampling compared to conventional active sampling methods (e.g., Summa™ canisters)

  • Lower cost.

  • Simpler sampling protocols.

  • Lower reporting limits without a premium price.

  • Longer time-integrated samples.

  • Very small size (discrete to deploy and easy to ship).

Benefits of WMS compared to other quantitative passive air samplers

  • Predictable uptake rates for less-common compounds.

  • Ability to measure total petroleum hydrocarbon/gasoline range organic compounds.

  • Minimal effect of moisture (very advantageous for subsurface monitoring).

  • Insensitive to wind velocity (very advantageous for outdoor and vent-pipe monitoring).

  • Ability to modify configuration to avoid the starvation effect when collecting subsurface samples.

  • Small diameter (easy to put in vent pipes or sub-slab probes).

Waterloo Membrane Sampler Products

The Waterloo Membrane Sampler (WMS) comes in several configurations:

WMS-SE WMS-LU WMS-VP WMS-TM
SVE Vent Pipe, Sewer Gas u
Standard soil material u
Sub-slab, porous fill material u u
Sub-slab with Vapor Pin® Capsule u
Wet and/or clay material u
Indoor/Outdoor Air u

WMS-SE

The regular solvent-extraction version of the WMS (WMS-SE) is an excellent choice for monitoring VOC vapor concentrations in indoor air, outdoor air, and vent pipes. Samples can be collected for extended periods because the strong sorbent used in this configuration and can be analyzed multiple times to measure analytes present at different concentrations within the calibration range.

WMS-LU

The low-uptake-rate version of the WMS (WMS-LU) is a great choice for monitoring VOC vapor concentrations in soil gas. The lower uptake rates mitigate the effect of sampler starvation that can occur when collecting soil gas samples and can measure analytes in soil gas in drier subsurface conditions.

WMS-VP

The Vapor Pin® version of the WMS (WMS-VP) is specifically designed and calibrated for measuring VOC vapor concentrations in sub-slab areas with the Vapor Pin® capsule. Switch between active and passive sampling with ease to gain full advantage of time-weighted average concentrations.

WMS-TM

The thick-membrane version of the WMS (WMS-TM) is a unique sampler designed for monitoring VOC vapor concentrations in soil gas in low-permeability or very wet soils. This sampler has the lowest uptake rates of the configurations available.

Waterloo Membrane Sampler Operating Procedures

Sampler Deployment Duration Calculator

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Contact us for a quote or to ask questions about the Waterloo Membrane Sampler.

Documentation

WMS Cut Sheet

WMS-VP Cut Sheet

WMS Sewer Gas Cut Sheet

ARTICLES PUBLISHED IN PEER-REVIEWED JOURNALS

McAlary, T., A. Inglis, B.G. Pautler, H. Hayes. 2025. Proof-of-Concept Testing of Passive Sampling of Sewer Gas for VOC Vapors Using the Waterloo Membrane Sampler™. Green Analytical Chemistry: 15, 100303. DOI:
10.1016/j.greenac.2025.100303.

Knight, M.A., M.A. Ioannidis, F. Salim,  T. Górecki, D. Pivin, 2023. Health Risks Assessment from Cured-in-Place Pipe Lining Fugitive Styrene Emissions in Laterals. J. Pipeline Syst. Eng. Pract., 14(1): 04022056. DOI: 10.1061/(ASCE)PS.1949-1204.0000690

BenIsrael, M., P. Wanner, R. Aravena, B. L. Parker, E. A. Haack, D. T. Tsao, K. E. Dunfield, 2019. Toluene biodegradation in the vadose zone of a poplar phytoremediation system identified using metagenomics and toluene-specific stable carbon isotope analysis. Int. J. Phytoremediat., 2019, 1, 60. DOI: 10.1080/15226514.2018.1523873

Salim, F., T. Górecki, 2019. Theory and modelling approaches to passive sampling. Environ. Sci.: Processes Impacts, 2019, 21, 1618. DOI: 10.1039/C9EM00215D

Salim, F., M. Ioannidis, A. Penlidis, T. Górecki, 2019. Modelling permeation passive sampling: intra-particle resistance to mass transfer and comprehensive sensitivity analysis. Environ. Sci.: Processes Impacts, 2019, 21, 469. DOI: 10.1039/C8EM00565F

Salim, F., T. Górecki, M. Ioannidis,  2019. New applications of mathematical model of a permeation passive sampler: prediction of the effective uptake rate and storage stability. Environ. Sci.: Processes Impacts, 2019, 21, 113. DOI: 10.1039/C8EM00397A

Huang, C., W. Shan, H. Xiao, 2018. Recent advances in passive air sampling of volatile organic compounds. Aerosol Air Qual. Res., 2018, 18, 602. DOI: 10.4209/aaqr.2017.12.0556

Salim, F., M. Ioannidis, T. Górecki, 2017. Experimentally validated mathematical model of analyte uptake by permeation passive samplers. Environ. Sci.: Processes Impacts, 2017, 19, 1363. DOI: 10.1039/C7EM00315C

Goli, O., T. Górecki, H. T. Mugammar, M. Marchesi, R. Aravena, 2017. Evaluation of the suitability of the Waterloo Membrane Sampler for sample preconcentration before compound-specific isotope analysis. Environ. Technol. Inno., 2017, 7, 141. DOI: 10.1016.j.eti.2017.02.001

McAlary, T. H. Groenevelt, S. Disher, J. Arnold, S. Seethapathy, P. Sacco, D. Crump, B. Schumacher, H. Hayes, P. Johnson, T. Górecki, 2015. Passive sampling for volatile organic compounds in indoor air-controlled laboratory comparison of four sampler types. Environ. Sci.: Processes Impacts, 2015, 17, 896. DOI: 10.1039/C4EM00560K

Marć, M., M. Tobiszewski, B. Zabiegała, M. de la Guardia, J. Namieśnik, 2015. Current air quality analytics and monitoring: A review. Anal. Chim. Acta, 2015, 853, 116. DOI: 10.1016/j.aca.2014.10.018

McAlary, T., H. Groenevelt, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, B. Schumacher, H. Hayes, P. Johnson, L. Parker, T. Górecki, 2014. Quantitative passive soil vapor sampling for VOCs – Part 4: Flow-through cell. Environ. Sci.: Processes Impacts, 2014, 16, 1103. DOI: 10.1039/C4EM00098F

McAlary, T., H. Groenevelt, P. Nicholson, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, B. Schumacher, P. Johnson, T. Górecki, I. Rivera-Duarte, 2014. Quantitative passive soil vapor sampling for VOCs – Part 3: Field experiments. Environ. Sci.: Processes Impacts, 2014, 16, 501. DOI: 10.1039/C3EM00653K

McAlary, T., H. Groenevelt, S. Seethapathy, P. Sacco, D. Crump, M. Tuday, B. Schumacher, H. Hayes, P. Johnson, T. Górecki, I. Rivera-Duarte, 2014. Quantitative passive soil vapor sampling for VOCs – Part 2: Laboratory experiments. Environ. Sci.: Processes Impacts, 2014, 16, 491. DOI: 10.1039/C3EM00128H

McAlary, T., X. Wang, A. Unger, H. Groenevelt, T. Górecki, 2014. Quantitative passive soil vapor sampling for VOCs – Part 1: Theory. Environ. Sci.: Processes Impacts, 2014, 16, 482. DOI: 10.1039/C3EM00652B

Seethapathy, S., T. Górecki, 2012. Applications of polydimethylsiloxane in analytical chemistry: A review. Anal. Chim. Acta, 2012, 750(31), 48. DOI: 10.1016/j.aca.2012.05.004

Seethapathy, S., T. Górecki, 2011. Polydimethylsiloxane-based permeation passive air sampler. Part I: Calibration constants and their relation to retention indices of the analytes. J. Chromatogr. A, 2011, 1218(1), 143. DOI: 10.1016/j.chroma.2010.11.003

Seethapathy, S., T. Górecki, 2010. Polydimethylsiloxane-based permeation passive air sampler. Part II: Effect of temperature and humidity on the calibration constants. J. Chromatogr. A, 2010, 1217(50), 7907. DOI: 10.1016/j.chroma.2010.10.057

ARTICLES PUBLISHED IN BOOK CHAPTERS

Armenta, S., M. del la Guardia, F. A. Esteve-Turrillas, 2020. Chapter 24 – Environmental applications (air). Solid-Phase Extraction. 2020, 647. DOI: 10.1016/B978-0-12-816906-3.00024-8

Marć, M., M. Śmiełowska, B. Zabiegała, 2017. Chapter 13 – Green Sample Collection. The Application of Green Solvents in Separation Processes. 2017, 379. DOI: 10.1016/B978-0-12-805297-6.00013-9

Reports Produced for the United States Department of Defense

NAVFAC, 2015. Passive Sampling for Vapor Intrusion Assessment. Technical Memo TM-NAVFAC EXWC-EV-1503

Geosyntec, 2015. Cost and report for development of more cost-effective methods for long-term monitoring of soil vapor intrusion to indoor air using quantitative passive diffusive-adsorptive sampling techniques. ESTCP project ER-200830, May 2015.

Geosyntec, 2014. Development of more cost-effective methods for long-term monitoring of soil vapor intrusion to indoor air using quantitative passive diffusive-adsorptive sampling. ESTCP Project ER-200830, June 2014.

Geosyntec, 2011. Demonstration of improved assessment strategies for vapor intrusion – passive samplers. SPAWAR Systems Center Pacific.

PAPER PRODUCED FOR THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

U.S. EPA, 2015. Engineering Issue Paper. Passive samplers for investigation of air quality: method description, implementation, and comparison to alternative sampling methods.

ACADEMIC THESES

Faten Salim, 2019. Modelling Permeation Passive Sampling, Ph.D., 2019, University of Waterloo.

Todd McAlary, 2014. Demonstration and Validation of the Use of Passive Samplers for Monitoring Soil Vapor Intrusion to Indoor Air, Ph.D., 2014, University of Waterloo.

Faten Salim, 2013. Novel Applications of the Waterloo Membrane Sampler (WMS) in Volatile Organic Compounds Sampling from Different Environmental Matrices, M.Sc., 2013, University of Waterloo.

Oana Goli, 2013. Compound Specific Isotope Ratio Analysis in Vapour Intrusion Studies using Waterloo Membrane Sampler (WMS), M.Sc., 2013, University of Waterloo.

Suresh Seethapathy, 2009. Development, Validating, Uptake Rate Modeling and Field applications of a New Permeation Passive Sampler, Ph.D., 2009, University of Waterloo.