New Hampshire Department of Environment Services (NHDES) made changes in 2018 and 2019 to stakeholder use of sample analytical methods for determination of Per- & Polyfluoroalkyl Substances (PFAS) in finished drinking water samples and other sample matrices. These changes are discussed below along with best practices for requesting PFAS analytical services for various sample matrices.
Drinking Water Samples:
Effective October 1, 2020, laboratory developed isotope dilution methods will no longer be accepted for the analysis of drinking water (DW) compliance monitoring samples. The methods that will be accepted include EPA 533, 537.1 and 537, as these EPA methods were developed specifically for drinking water samples. Each of these PFAS analytical methods is used to determine a distinct list of PFAS compounds.
The absolute minimum list of PFAS compounds for NH drinking water samples include the four PFAS compounds with state MCLs (see below). In prior guidance, NHDES recommended analysis for as many compounds as feasible, noting that samples should, if possible, include at least the nine PFAS compounds identified by EPA 537 and 537.1 (issued in November 2018). Subsequently NHDES stated in a May 2019 waste sampling guidance that limiting reporting to nine or fewer PFAS compounds will limit the understanding of potential PFAS sources, fate, and transport. As such and given the increased analytical capacity and the emerging understanding of release types and contaminant fate and transport, NHDES recommends reporting as many PFAS compounds as feasible to develop a more comprehensive conceptual site model associated with PFAS release(s).
The NHDES waste sampling guidance (dated May 2019) also addressed the concerns that use of EPA 537.1 (a non-isotope approach) may not be appropriate for groundwater samples collected as part of site investigations due to potential matrix interference effects. The most recent EPA drinking water method for PFAS, EPA 533 (released in December 2019) uses isotope dilution for determination of 25 PFAS compounds. This method includes the NH 4 DW MCL PFAS compounds and the original NH 9 PFAS compounds. For these reasons, selection of EPA 533 for determination of 25 compounds achieves the NHDES recommended approach. These compound lists are shown below.
Refer to the NHDES Laboratory Testing Guidelines PFAS for Public Drinking Water Supplies (dated September 2020), available at: https://www4.des.state.nh.us/nh-pfas-investigation/wp-content/uploads/PFAS-Testing-Guidance_rev4.pdf
|NH PFAS MCL Compounds||NH-9 PFAS Compounds||EPA 533 Compounds|
|PFOA 12 ppt||PFOA PFBA||NH-9 plus|
|PFOS 15 ppt||PFOS PFBS||PFDA 4:2FTS|
|PFNA 11 ppt||PFNA PFPeA||PFUnA 6:2FTS|
|PFHxS 18 ppt||PFHxS PFHxA||PFDoA 8:2FTS|
Non-Drinking Water Samples:
Non-drinking water samples include samples collected from petroleum sites, waste sites, landfills, industrial and municipal wastewater, and may include soils, sludges, compost and any tissue or vegetative samples. Currently EPA has not released PFAS analytical methods for these types of samples other than Method 8327 for non-potable water which has very limited application. Laboratory developed isotope dilution (ID) methods have evolved to meet this need along with the U.S. Department of Defense (DoD) QSM 5.3 quality control guidelines (Table B-15 for PFAS). The PFAS isotope based analytical methods have been designed to accommodate matrix interferences common in these types of samples. While the NHDES Waste Site Guidance (May 2019) indicates use of the isotope method it also indicates use of EPA 537.1, which is a non-isotope approach designed specifically for finished drinking water samples. Use of EPA 537.1 on any samples other than finished DW samples is not suitable as sample matrix effects impact sample processing time and expense and often result in data quality concerns. Selection of the more rugged Isotope analytical methods specifically designed for sample matrix effects offers a more suitable approach.
When requesting PFAS sample analyses, NHDES prefers that analytical methods use isotope dilution following the protocols for PFAS by LC/MS/MS compliant with DOD Quality Systems Manual (QSM) 5.2 (or later) Table B-15. Please specify the Isotope Dilution approach for sample matrices other than finished DW samples, as well as the list of PFAS compounds to be reported. The DoD list of 24 PFAS compounds is commonly requested. Alpha offers a longer list of 40 PFAS compounds to support NHDES recommendations for analysis of other PFAS to aid in understanding and delineating PFAS releases.
Refer to the NHDES Waste Site Laboratory Guidance and FAQs (dated May 2019), available at: https://www4.des.state.nh.us/nh-pfas-investigation/wp-content/uploads/2019/05/201905_Lab-Guidance-1.pdf
For more information, please contact your Alpha Analytical project manager, sales representative or our customer service team at 508-898-9220.