Sampling and Analysis for PFAS
Oct. 14 2018
Per- and polyfluorinated alkyl substances (PFAS) are man-made chemicals that are gaining a substantial amount of recognition as environmental contaminants. They have been used in a variety of applications due to their stability under extreme heat and chemical stress, and their surfactant properties. PFAS is used in:
- Industrial polymers (Teflon™)
- Stain repellents (Scotch Guard™)
- Aqueous firefighting foams (AFFF)
Of particular concern are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which are persistent in the environment and can bioaccumulate, causing toxicity in some animals. PFAS are of particular interest recently because of their emergence as compounds of environmental concern at many sites across North America and around the world.
Because of the physical and chemical behavior of PFAS in environmental samples (water, soils and tissue), they pose unique analytical challenges. These same physical and chemical characteristics extend these challenges to field sampling protocols and, if not taken into consideration, lead to unreliable sample integrity and data variability. Ultimately, analytical data will not be representative of the true site condition.
Due to their unique chemical properties, PFAS have been widely used both commercially and in many industries since the late 1940s. As a result, the presence of PFAS in many materials commonly found on-site during environmental sample collection activities is a potential source of sample contamination that is not representative of the site condition. As regulatory requirements drive the need for trace level sensitivity in PFAS measurements, the probability of false positives during PFAS monitoring increases.
Historically, sample guidance has suggested a very rigorous regime of austerity when it came to materials such as personal care products used during or even prior to PFAS sample collection. More recently, and with the benefit of years of experience in sampling and analyzing for PFAS, many environmental practitioners are adopting a precautionary “common sense” approach to sample collection in order to avoid false positive PFAS results.
In doing so, field sampling materials can be divided into three categories: prohibited; acceptable; and materials requiring screening
- Prohibited Materials are items or materials that should not be used within the sampling environment because PFAS were used in their manufacture and they have been demonstrated to be sources of PFAS contamination. Examples of prohibited materials include: waterproof field books, Decon 90® Detergent, Teflon materials (e.g. PTFE-lined caps for sample containers), etc.;
- Acceptable Materials are items or materials that have been demonstrated not to be sources of PFAS contamination and are adequate for field sampling purposes. Examples of acceptable materials include: Alconox® and/or Liquinox® Detergents, HDPE or HDPP materials, etc.; and
- Materials That Require Screening are items or materials that have the potential to contaminate samples with PFAS but there is insufficient scientific data to prove this.
Field sampling staff should also consider two sub-categories for the materials noted above:
- Materials that will come in direct contact with the sample
- Materials that will not come in direct contact with the sample.
In general, it is best practice to avoid obvious sources of PFAS in your sampling environment. Use PFAS-free sample containers that have been proofed by Bureau Veritas. As well, Bureau Veritas Laboratories provides specially purified and proofed PFAS-free water for field quality control purposes. Finally, while it is important to protect against extraneous sources of PFAS contamination, there is no substitute for a robust and rigorous field quality assurance program to demonstrate that there has been no contribution of PFAS from field sampling materials and activities.
Health Canada has issued the following drinking water screening values for specific PFAS.
Table 1: PFAS Screening Values in Drinking Water
|PFAS NAME||ACRONYM||SCREENING VALUE (mg/L)||SCREENING VALUE (μg/L)|
Health Canada has also issued the following soil screening values for PFAS.In July 2018, after reviewing new studies suggesting that perfluorononanoic acid (PFNA) can cause adverse health effects at lower concentrations than previously thought, Health Canada lowered PFNA's drinking water screening value to 0.02 μg/L.
Table 2: PFAS Screening Values in Soil (mg/kg)
|PFAS NAME||AGRICULTURAL/RESIDENTIAL/ PARKLAND LAND USE||COMMERCIAL LAND USE||INDUSTRIAL LAND USE|
Table 3: Stage 10 Amendments to British Columbia's CSROn November 1, 2017, British Columbia became the first jurisdiction in Canada to regulate PFAS in contaminated sites with the amendment of its Contaminated Sites Regulations (CSR).
|MATRIX||PFOA (ug/L)||PFOS (ug/L)||PFBS (ug/L)|
The United States Environmental Protection Agency (USEPA) has issued health advisories for acceptable levels of PFOA and PFOS for short term exposure. Many States have additionally established drinking water guidelines for the compounds listed in Table 4.
Table 4: Drinking Water Guidelines by State
|USEPA Office of Water||0.07 (combined)||No Value||No Value||No Value||No Value||No Value|
|USEPA Region 2||No Value||0.1||No Value||No Value||No Value||No Value||No Value|
|Alaska||0.6||0.4||No Value||No Value||No Value||No Value||No Value|
|California||0.2||0.4||No Value||No Value||No Value||No Value||No Value|
|Delaware||0.2||0.4||No Value||No Value||No Value||No Value||No Value|
|Illinois||0.2||0.4||No Value||No Value||No Value||No Value||No Value|
|Maine||0.56||0.13||No Value||No Value||No Value||No Value||No Value|
|Michigan||0.07 (combined)*||No Value||No Value||No Value||No Value||No Value|
|Minnesota||0.027||0.035||7||3||0.027||No Value||No Value|
|New Hampshire||0.2||0.4||No Value||No Value||No Value||0.013||No Value|
|North Carolina||No Value||2||No Value||No Value||No Value||No Value||0.14*|
|Ohio||No Value||0.4||No Value||No Value||No Value||No Value||No Value|
|Oregon||300||24||No Value||No Value||No Value||No Value||No Value|
|Texas||0.56||0.29||No Value||No Value||No Value||No Value||No Value|
|Vermont||No Value||0.02||No Value||No Value||No Value||No Value||No Value|
The UK Health Protection Agency (HPA) and the Department of Environmental Protection in Germany have advised the following maximum acceptable concentrations of PFOA and PFOS in drinking water.
Table 5: Drinking Water Guidelines in Europe
|AGENCY||PFOA (ug/L)||PFOS (ug/L)|
|German||0.1||(sum of PFOA and PFOS)|
Sample Containers/Hold Times
Samples should be collected in high density polyethylene (HDPE) bottles, provided by the laboratory, and fitted with an unlined (Teflon-free) polypropylene screw cap. A minimum of 125 mL of sample is required for low level PFAS analysis. The sample hold time is 14 days with proper storage (1-6° C, minimum exposure to light). Sample containers should be filled completely, to minimize surface-to-volume ratios, thereby reducing the relative impact of adsorption to container walls.
In accordance with USEPA Method 537, chlorinated drinking water samples may require preservation with Trizma® at the time of sampling, to quench the effects of residual chlorine and to buffer the sample at a pH of approximately 7.
Soil and Tissue
Samples should be collected in high density polyethylene (HDPE) wide-mouth bottles, provided by the laboratory, and fitted with an unlined (Teflon-free), polypropylene screw cap. A minimum of 50 g of sample is required. In the absence of any regulated sample hold time, Bureau Veritas adheres to a 28 day hold time for solids and tissues with proper storage (1-6° C, minimum exposure to light).
Because of the ubiquitous nature of PFAS compounds in many modern materials, all batches (lots) of PFAS sample containers provided by Bureau Veritas are “proofed” by the laboratory to demonstrate that they are PFAS-free. Similarly, water used in the field to generate quality control (QC) samples should be PFAS-free. For a nominal fee, Bureau Veritas will provide PFAS-free water which has been “proofed” by the laboratory and is certified to be PFAS-free.
Bureau Veritas provides analyses for PFAS on a diverse range of environmental matrices, including among others: aqueous firefighting foams (AFFFs), drinking water, groundwater, leachate, soil and other solids and tissue.
Low level water samples undergo solid phase extraction (SPE), to extract, clean up and concentrate the parameters of concern. The extract is then analyzed by isotope dilution liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS).
Water samples having higher contaminant concentrations (often requiring dilution) may be analysed by direct injection isotope dilution LC/MS/MS.
Soil, solids and tissues are homogenized, and then undergo a solid/liquid extraction. Interferences are removed from the liquid extract using solid phase extraction (SPE). The resultant extract is then concentrated and analyzed by isotope dilution LC/MS/MS.
Bureau Veritas currently reports up to 32 PFAS including precursors and replacement PFAS (see Table 6). Reporting limits (RLs) and method detection limits (MDLs) for these parameters have been validated at the low parts-per-trillion (ppt).
Analytical Turnaround Time (TAT)
Standard TAT: 10 business days.
Priority TAT: By pre-arrangement only.
Bureau Veritas is accredited by the Standards Council of Canada (SCC), the US National Environmental Laboratory Accreditation Program (NELAP) and the US Department of Defense Environmental Laboratory Accreditation Program (DoD-ELAP) for the analysis of PFAS in environmental matrices.
Table 6: Regular PFAS Analysis Packages
|Carboxylic and Sulfonic Acids||Perfluorobutanoic acid||PFBA|
|Carboxylic and Sulfonic Acids||Perfluorobutanesulfonic acid||PFBS|
|Carboxylic and Sulfonic Acids||Perfluorodecanoic acid||PFDA|
|Carboxylic and Sulfonic Acids||Perfluorododecanoic acid||PFDoA|
|Carboxylic and Sulfonic Acids||Perfluorodecanesulfonic acid||PFDS|
|Carboxylic and Sulfonic Acids||Perfluoroheptanoic acid||PFHpA|
|Carboxylic and Sulfonic Acids||Perfluoroheptanesulfonic acid||PFHpS|
|Carboxylic and Sulfonic Acids||Perfluorohexanoic acid||PFHxA|
|Carboxylic and Sulfonic Acids||Perfluorohexanesulfonic acid||PFHxS|
|Carboxylic and Sulfonic Acids||Perfluorononanoic acid||PFNA|
|Carboxylic and Sulfonic Acids||Perfluorononane sulfonic acid||PFNS|
|Carboxylic and Sulfonic Acids||Perfluorooctanoic acid||PFOA|
|Carboxylic and Sulfonic Acids||Perfluorooctanesulfonic acid||PFOS|
|Carboxylic and Sulfonic Acids||Perfluoropentanoic acid||PFPeA|
|Carboxylic and Sulfonic Acids||Perfluoropentane sulfonic acid||PFPeS|
|Carboxylic and Sulfonic Acids||Perfluorotetradecanoic acid||PFTeDA|
|Carboxylic and Sulfonic Acids||Perfluorotridecanoic acid||PFTrDA|
|Carboxylic and Sulfonic Acids||Perfluoroundecanoic acid||PFUnA|
|Fluorotelomers||4:2 Fluorotelomer sulfonic acid||4:2-FTS|
|Fluorotelomers||6:2 Fluorotelomer sulfonic acid||6:2-FTS|
|Fluorotelomers||8:2 Fluorotelomer sulfonic acid||8:2-FTS|
|Extended List||(= Standard List +)|
|Precursors||N-Ethylperfluorooctane sulfonamido acetic acid||EtFOSAA|
|Precursors||N-Methylperfluorooctane sulfonamido acetic acid||MeFOSAA|
|Complete List||(= Extended List +)|
|Replacement Compounds||9-Chlorohexadecafluoro-3-oxanonane-1-sulfonate||9Cl-PF3ONS (F-53B major)|
|Replacement Compounds||11-Chlororeicosafluoro-3-oxaundecane-1-sulfonic Acid||11Cl-PF3OUdS (F-53B minor)|
|Replacement Compounds||4,8-dioxa-3H-perfluorononanoic acid||ADONA|
|Replacement Compounds||Hexafluoropropyleneoxide dimer acid||HFPO-DA (GenX)|