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.