PFAS Sampling: Guidance for Getting Accurate Test Results

Jimmy Gibson

Environmental Services Practice Leader

Charles Gaddy

Environmental Engineer and Professional Geoscientist

Under the new national regulations aimed at eliminating PFAS from drinking water, public water systems must test and monitor their water to determine their levels of these per- and polyfluoroalkyl substances.

Because PFAS are ubiquitous and the allowable levels are low, it’s important to use the appropriate precautions and care during sample collection to avoid cross-contamination that could cause false-positive results.

PFAS are everywhere — and persistent

PFAS, man-made fluorinated organic chemicals, are widespread in products people use frequently, including clothing, carpeting and furniture with oil and water repellents; fast-food packaging and nonstick cookware; and personal products such as sunblock, bug sprays, skin moisturizers and makeup.

PFAS have been found throughout the environment in groundwater, surface water, wastewater, soil and sediment. To help protect the accuracy of lab analytical results, collecting samples from water, soil or sediment requires special considerations and processes to prevent the potential for cross-contamination.

Unique sampling protocols required

Here are some steps to follow when collecting samples for analysis to help guard against false-positive laboratory results:

1. Use sampling containers supplied by the laboratory that will perform the analysis.
   • Bottles provided may be made of high-density polyethylene plastic (HDPE) with lids that are free of TeflonTM.
   • Bottles for analysis by EPA Methods 1633, 533 or 537.1 contain a preservative such as ammonium acetate or Trizma; bottles should not be overfilled because that could dilute the sample preservative.

2. Sample with dedicated or single-use equipment.
3. Use sampling equipment that is documented to be plastic-free: Stainless steel, glass, HDPE, polypropylene, polyvinyl chloride, neoprene, silicone and acetate are preferred materials.
4. Wear disposable gloves during sampling that are documented to be PFAS-free: Powderless nitrile gloves are preferred and should be changed between sample collections.
5. Decontaminate any reusable or dedicated equipment between uses using water and detergents that are documented to be PFAS-free.
6. Choose clothing carefully.
   • Do not wear water-resistant clothing or water-resistant PPE.
   • Do not wear clothes that have been laundered using fabric softeners.
   • Do not wear sunblock or bug spray.
   • Do not wear makeup or use skin moisturizer.
   • Do not wear perfume, cologne or other body sprays.
   • Do not use “Right in the Rain” field books or pens.

7. Collect Field Quantity Control samples in a similar manner to site samples.

Work with your laboratory to determine any additional unique collection protocols to use during sampling.

How Freese and Nichols Can Help

With our team’s expertise and experience in environmental science and water treatment, we can assist you with all aspects of PFAS regulatory compliance. Freese and Nichols PFAS experts can help with sample collection protocols as well as conducting sampling.

To Learn More:

• Contact David Jackson, david.jackson@freese.com, Viraj deSilva, viraj.desilva@freese.com or Jimmy Gibson, jimmy.gibson@freese.com
• Visit our PFAS services page

Jimmy Gibson, PE, is Environmental Services Practice Leader, based in Fort Worth.

Charles Gaddy, PE, PG, is an Environmental Engineer and Professional Geoscientist with experience in regulatory compliance, based in Fort Worth.