EnviroMail 20 USA

PFAS EPA Method 1633: Answers to six key questions

The U.S. Environmental Protection Agency (EPA) recently published the “PFAS Strategic Roadmap: EPA’s Commitment to Action 2021-2024 1” which established defined goals and target completion dates to address PFAS concerns through research, restriction, and remediation.

01 OCT 2022 ALS

In tandem with the publication of the roadmap, EPA Office of Water has finalized Method 1633Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/ MS2.

There are many lingering questions about the method – how it should be approached in the short term, and planning for its long-term adoption.

These are answers to six of the most frequently asked questions on EPA Method 1633.

 

What is the purpose of the new method?

The need for standard PFAS methods for different matrices became clearer as the ubiquitous nature of PFAS in environmental media and wastes was better understood. EPA Method 1633 is intended to provide standard procedures for the sampling and analysis of PFAS in a wide range of sample types: surface water, groundwater, wastewater, leachate, fish tissue, soil, sediment, and biosolids. It also analyzes for a larger number of PFAS compounds – 40 in total, and uses isotope dilution techniques to more accurately quantify PFAS.Additionally, Method 1633 addresses analytical challenges that are unique to PFAS, such as:

  • Linear and branches isomer occurrence for some PFAS
  • False-positive results for PFOS
  • Aqueous samples with particulates
  • Precursor transformations during sample preservation and storage
  • PFAS adherence to the sample container wall and stratification within the container

It is hoped that the success of Method 1633 in addressing these analytical challenges will help to address them in other PFAS methods.

 

Will this method replace EPA Method 537.1 or EPA 533?

EPA Method 1633 complements, but does not replace, existing PFAS methods such as:

EPA Method 1633 has been developed for non-drinking water aqueous matrices (surface water, groundwater, wastewater influent/effluent, landfill leachate), fish tissues, biosolids, soils, and sediments. It complements existing PFAS methods by analyzing a larger number of PFAS compounds and a greater variety of sample matrices.

In summary:

  • EPA Method 1633 is a multi-laboratory validated method that has been specifically designed for wastewater analysis. It is endorsed by the EPA.
  • Modified EPA Method 537.1 and EPA Method 533 are drinking water methods that may be adapted for wastewater analysis. While acceptable for SDWA testing, they may not be appropriate for wastewater analysis because they have not been validated for wastewater matrices.

 

What compounds are covered under EPA Method 1633?

EPA Method 1633 analyzes over 40 PFAS compounds, including:

Compound

Abbreviation

CAS number

Perfluorobutanoic acid 

PFBA

375-22-4 

Perfluoropentanoic acid 

PFPeA

2706-90-3 

Perfluorohexanoic acid 

PFHxA 

307-24-4 

Perfluoroheptanoic acid 

PFHpA 

375-85-9

Perfluorooctanoic acid 

PFOA

335-67-1

Perfluorononanoic acid 

PFNA

375-95-1

Perfluorodecanoic acid 

PFDA

335-76-2 

Perfluoroundecanoic acid 

PFUnA 

2058-94-8

Perfluorododecanoic acid 

PFDoA 

307-55-1 

Perfluorotridecanoic acid 

PFTrDA

72629-94-8

Perfluorotetradecanoic acid 

PFTeDA 

376-06-7

Perfluorobutanesulfonic acid 

PFBS 

375-73-5

Perfluoropentanesulfonic acid 

PFPeS

2706-91-4

Perfluorohexanesulfonic acid 

PFHxS

355-46-4

Perfluoroheptanesulfonic acid 

PFHpS 

375-92-8 

Perfluorooctanesulfonic acid 

PFOS

1763-23-1

Perfluorononanesulfonic acid 

PFNS 

68259-12-1

Perfluorodecanesulfonic acid

PFDS 

335-77-3

Perfluorododecanesulfonic acid

PFDoS 

79780-39-5

1H,1H, 2H, 2H-Perfluorohexane sulfonic acid

4:2FTS

757124-72-4

1H,1H, 2H, 2H-Perfluorooctane sulfonic acid 

6:2FTS

27619-97-2

1H,1H, 2H, 2H-Perfluorodecane sulfonic acid 

8:2FTS 

39108-34-4

Perfluorooctanesulfonamide 

PFOSA 

754-91-6

N-methyl perfluorooctanesulfonamide 

NMeFOSA

31506-32-8

N-ethyl perfluorooctanesulfonamide 

NEtFOSA 

4151-50-2

N-methyl perfluorooctanesulfonamidoacetic acid 

NMeFOSAA 

2355-31-9 

N-ethyl perfluorooctanesulfonamidoacetic acid

NEtFOSAA

2991-50-6

N-methyl perfluorooctanesulfonamidoethanol 

NMeFOSE

24448-09-7

N-ethyl perfluorooctanesulfonamidoethanol 

NEtFOSE

1691-99-2

Hexafluoropropylene oxide dimer acid

HFPO-DA

13252-13-6 

4,8-Dioxa-3H-perfluorononanoic acid 

ADONA

919005-14-4

Perfluoro-3-methoxypropanoic acid 

PFMPA

377-73-1 

Perfluoro-4-methoxybutanoic acid 

PFMBA 

863090-89-5 

Nonafluoro-3,6-dioxaheptanoic acid 

NFDHA

151772-58-6

9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid 

9Cl-PF3ONS

756426-58-1 

11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid

11Cl-PF3OUdS 

763051-92-9 

Perfluoro(2-ethoxyethane)sulfonic acid 

PFEESA 

113507-82-7

3-Perfluoropropyl propanoic acid 

3:3FTCA

356-02-5

2H,2H,3H,3H-Perfluorooctanoic acid

5:3FTCA

914637-49-3

3-Perfluoroheptyl propanoic acid 

7:3FTCA 

812-70-4

 

Timeline of PFAS Methods

2008 Office of Water Method 537 for 14 PFAS in drinking water
2018 Office of Water Method 537.1 for 18 PFAS in drinking water
2019 Office of Water Method 533 for 25 PFAS in drinking water, includes short-chain PFAS unmeasurable by Method 537.1
2021 Office of Solid Waste Method 8327 for 24 PFAS in groundwater, surface water, and wastewater
2021 Office of Water 1st Draft Method 1633 for 40 PFAS in surface water, groundwater, wastewater, leachate, fish tissues, biosolids, soils, and sediments
2022 Office of Water 2nd Draft Method 1633 revised in response to feedback, comments, and questions submitted by parties testing the new draft method
2024 The EPA finalizes Method 1633 for analysis of PFAS

 

What programs are requiring Method 1633?

Currently, EPA Method 1633 is yet not required for PFAS compliance monitoring by any EPA regulation, although it is the preferred method for some programs, including NPDES.

The National Pollutant Discharge Elimination System (NPDES) recommends using EPA Method 1633 for analyzing PFAS in permits. This is because there are currently no approved PFAS methods in 40 CFR Part 136.

Facilities with a federally issued NPDES discharge permit can use Method 1633 for permit application testing and ongoing discharge monitoring. Additionally, states issuing NPDES permits will receive guidance from EPA recommending the use of Method 1633.

The DoD Environmental Data Quality Workgroup has determined that EPA Method 1633 meets the precision, accuracy, and limits of quantitation needed to support sound decision making. All new contracts and task orders after December 31, 2021, shall require the use of Method 1633 for the analysis for PFAS in matrices other than drinking water using a laboratory accredited to the method/matrix/analyte by the DoD Environmental Laboratory Accreditation program (ELAP). All existing projects are encouraged to use Method 1633 for PFAS analysis in matrices other than drinking water when ELAP-accredited laboratories become available.

 

Are federal agencies and states offering accreditation for EPA Method 1633?

EPA does not currently regulate PFAS under the Clean Water Act, meaning there are no laboratory certification requirements for PFAS analysis at this time. The U.S. Department of Defense (DOD) has a PFAS laboratory certification program through its Environmental Laboratory Accreditation Program (ELAP).

States tend to certify laboratories in order to support the monitoring of federally regulated contaminants. As a result, most states have yet to develop a PFAS laboratory certification program. Some state agencies, such as the Alaska Department of Environmental Conservation, are certifying PFAS laboratories based on their DOD-ELAP accreditation. Some states such as the Commonwealth of Pennsylvania are offering certification for the draft version.

 

ALS Environmental is DOD-ELAP accredited for PFAS analysis.

Methods offered include:

  • EPA Method 1633
  • EPA 537.1
  • EPA 537M
  • EPA 533
  • EPA 8327
  • ASTM D 7979
  • ASTM D 7968

 

Does the method include changes in sampling, preservation, or hold times?

Yes, Method 1633 has requirements for sample container, preservation, temperature, and holding time that differ from existing methods. The following table lists the requirements for aqueous samples for Method 1633 and existing drinking water methods.

 

PFAS EPA Methods - Sampling Requirements

Method 8327 Method 1633 Method 537.1 Method 533
Water sample collection 2 x 500mL HDPE bottles with Linerless HDPE or polypropylene caps 1 x 250mL polypropylene bottle with polypropylene screwcap 1 x 250mL polypropylene bottle with polypropylene screwcap
Preservation None Trizma® preset crystals or equivalent Ammonium acetate
Hold time and temp Shipping: 48 hours at 6° C or lower; Lab: 90 days from collection at -20° C OR 28 days from collection at 4° C Shipping: 10° C or lower; Lab: 6° C or lower until extraction; extract within 14 days of collection; Samples must not be frozen Shipping: 2 days at 10° C or lower; Lab: 6° C or lower until extraction; extract within 28 days of collection; Samples must not be frozen

 

 

How will the transition to Method 1633 affect sample turnaround time and lab capacity?

EPA Method 1633 is more intensive for the laboratory in two primary ways: first, there are more target analytes (40 compared to the current 14-25); second, the quality control criteria is more stringent than existing methods. Both of these aspects of the draft method have the potential to impact a laboratory’s capacity and sample turnaround time. EPA Method 1633 enables expanded characterization of more PFAS compounds in more matrices. It is without a doubt the method of the future!

Complete your PFAS analyses on time. ALS PFAS testing is performed in accordance with both EPA and ASTM methods are reported in 10 days or less, with rush services down to 3 days available.

 

 

 

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