Aqueous film-forming foams (AFFF) are perfluorinated compound (PFC)-containing chemicals, which have been in use since the 1960s for hydrocarbon fire suppression. Historically, AFFF compounds most frequently associated with contamination at AFFF sites include:
- Perfluoroalkyl acid (PFAA) — Carboxylates and sulfonates, which could be part of AFFF formulations or breakdown products from larger AFFF compounds
- Perfluorinated carboxylates (PFCAs) — Fluorotelomer sulfonate (FTS) based with degradation products that produce FTS and C7 or shorter chain perfluorinated carboxylates (PFCAs)
- Perfluoroalkyl sulfonates (PFSAs)— Perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorobutane sulfonate (PFBS) are examples of compounds in this class
When groundwater contamination crosses AFFF site boundaries, it may require analysis of the contamination of the surrounding environment and human exposure. Historic AFFF use has left a legacy of sites with significant contamination issues, and relevant agencies continue to determine how and what to monitor on these sites. Since the early 2000’s the composition and toxicity of per- and polyfluoroalkyl substances (PFASs) related to AFFF products has been a subject of considerable study and guidance/regulation. At a federal level, the focus has been on the highly bioaccumulative substances: perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), with provisional guidance set (and re-set) for drinking water. Other jurisdictions have applied guidance for a broader range of compounds. The regulatory trend is towards a lowering of drinking water guidelines over time for PFOS and PFOA, and much lower guidelines for other environmental matrices (such as fish advisory levels and related water and sediment specifications) in non-federal jurisdictions. Currently, federal governments continue revising regulatory guidance to cover an expanded list of AFFF-related compounds.
AFFF products continue to be used due to the vital role they play in safety and asset protection. Many AFFF products still exist, often FTS based, with little disclosure of ingredients. Reformulation of AFFF products to eliminate PFOS, PFOA or longer chain PFASs has occurred in the past decade. Significant change in isolating the application areas of AFFF from the environment has occurred as well. These compounds, both from a historic site contamination perspective as well as ongoing use, will remain an important area of environmental focus.
AXYS offers the widest range of per- and polyfluorinated compound (PFC) analysis of any commercial lab. All AXYS methods relating to AFFF contamination are LC-MS/MS methods using isotope-dilution quantification; an attribute that has been identified as best practice in all major PFC studies. This attribute is especially important for AFFF sites where very high levels of chemicals may be present in groundwater, creating the potential for significant suppression or enhancement of analytical results. The major PFCs of interest in relation to AFFF contamination are C4, C6, C8 perfluorooctane sulfonates (PFOS), C4 to C9 perfluoro carboxylic acids (PFCAs), and 4:2 to 8:2 fluorotelomer sulfonates (FTS) — AXYS has extensive experience in analysis of these compounds to support AFFF site investigations.
Aqueous samples containing fluorinated surfactants are complex matrices with high potential for analytical uncertainty arising from sub-sampling, high analyte concentrations, and considerable concentrations of compounds not routinely measured. AXYS has developed a specific method for use primarily in rapid and accurate characterization of sites affected by AFFF. We use techniques that provide exceptional detection limits for routine or difficult samples:
- Direct injection method for samples with very high analyte levels
- Specific sampling guidance for AFFF site waters to avoid heterogeneity issues, container loss, and results within calibration ranges
- Optimized sample detection limits
- Custom method development
- Wide range of matrices analyzed
The direct injection method analyses includes evaluation of these compounds:9 perfluoroalkyl carboxylates (PFCA)
3 perfluoroalkyl sulfonates (PFSA)
Perfluorooctane sulfonamide (PFOSA)
Perfluorohexanoate (PFHxA)Perfluorooctanesulfonate (PFOS)
Perfluorooctane sulfonamide (PFOSA)
Assessing the Presence of AFFF at Airports
2007 to present – AXYS has supported a number of Transport Canada, DND and Defense Construction Canada (DCC) consultants at multiple sites in providing aqueous and soil analysis to assess AFFF contamination and monitor groundwater remediation.
Surveying AFFF Aqueous Concentrations
AXYS conducted a preliminary survey of PFAAs drinking water concentrations for 21 Canadian Forces Bases using AFFF.
Analysis of FFAA Compounds Content in AFFF at DND AFFF Storage Facilities
900 AFFF and AFFF aqueous rinse samples from storage tanks were analyzed in 2008 – 2010. Survey included all DND bases with AFFF storage. Sample analyses were performed to determine PFOS and other perfluorinated compound content in AFFF, to meet regulatory requirements of <20 ppm PFOS content in AFFF product.