PFAS Sample Collection


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PFAS Sample Collection

By: Steve Williamson, CPG

As discussed in another article in this newsletter, some states have established drinking water standards for per-and polyfluoroalkyl substances (PFAS), or they are in the process of doing so. The standards being adopted are low – in the nanograms per liter (ng/L) or parts-per-trillion (ppt) range – and require very low laboratory detection limits. The US EPA has a current drinking water advisory of 70 ppt for perfluorooctanoic acid (PFOA) and/or perfluorooctane sulfonate (PFOS). In a recent webinar for local leaders, the Michigan Department of Environmental Quality used the analogy that one ppt is the same as one drop in 20 Olympic swimming pools. The low laboratory detection limits and the ubiquitous nature of these compounds have real implications for conducting sampling and analyses of environmental media

A Very Brief Primer on the Use and Presence of PFAS Compounds

PFAS compounds are just about everywhere. They have been used for decades in many industries: electronics, aerospace/defense, building/construction, alternative energy, automotive, semiconductors, military, healthcare, personal care products (e.g. deodorant and makeup), food packaging (e.g. microwave popcorn bags), non-stick cookware, outdoor apparel/equipment (e.g. GORE TEX), pharmaceuticals, stain resistant carpeting and furniture, and in aqueous film forming foams (AFFFs) used for fire training and firefighting. They have both water and oil resistant qualities. They are persistent in the environment and they bioaccumulate in body proteins. PFAS compounds are present in lakes, rivers and oceans; in soil; in wastewater treatment plant effluent; in polar snow and ice; and in wildlife. A striking revelation is that these compounds are present in the blood and tissue of polar bears in some of the most remote areas in the world.  PFAS compounds are in our food, drinking water, and in our blood serum.

Groundwater Sample Collection Considerations

Because these compounds are ubiquitous and the laboratory detection limits utilized are so low, the potential for inadvertent cross contamination of environmental samples is great. Cross contamination during sampling may occur from sampling equipment (i.e., bailers, pumps, tubing, containers, spoons, gloves, filters, drilling equipment, passive samplers, and decontamination water), from the sampling staff themselves (for example, from makeup or deodorant), or from airborne sources in the vicinity of the sample collection points. As such, there are special considerations that must be taken when sampling for PFAS compounds. These include the following:

  • Sampling equipment, sample bottles, and caps cannot contain Teflon
  • Samples should not be filtered, as filters may contain PFAS compounds
  • Disposable (single use) polyethylene or silicone sampling equipment should be used
  • PFAS adsorb to glass, so glass sampling containers cannot be used; high density polyethylene or polypropylene containers should be used.
  • Secondary cross contamination may occur from several sources:
    • PPE
    • Clothing
    • Waterproof logbooks and notebook paper
    • Permanent markers
    • Post-its
    • Paper towels
    • Stain- and water-resistant clothing/boots
    • Insect repellents
    • Sunscreen, moisturizers, makeup
    • Blue ice
  • Well washed clothing should be worn (more than six cycles but not washed with fabric softeners)
  • In general sunscreen, lotions, moisturizers and makeup should be avoided before or during sampling and bottle handling
  • Non-powdered nitrile gloves should be worn

Even the simple act of picking up a breakfast sandwich on the way to a site prior to sampling can result in PFAS contamination of skin, clothing, and air in the vehicle, and without necessary precautions can result in cross contamination of samples.

Detailed guidance for PFAS sample collection has been developed by several organizations, including the Interstate Technology Regulatory Council, Battelle Memorial Institute, Michigan DEQ, and the National Ground Water Association (free to members).  Planning and experience are necessary for the successful sampling and analysis of PFAS in environmental media.  For more information or to discuss your sampling needs, contact the author.

Published in Cox-Colvin’s April 2019 Focus on the Environment newsletter.


Steve Williamson is a Senior Scientist with Cox-Colvin & Associates, Inc. He holds a BS degree in Environmental Health and an MS degree in Hydrogeology from Wright State University. Mr. Williamson has over 30 years' experience working on brownfields, solid and hazardous waste, and groundwater contamination projects in Ohio and the Midwest.