Laboratory

US EPA Method 1633

Mar. 24 2022

In September 2021, the United States Environmental Protection Agency (US EPA) issued a draft method for per- and polyfluoroalkyl substances (PFAS) [1]. US EPA Method 1633 is the first PFAS method issued by the US EPA for non-drinking water matrices. Until now, regulated entities and environmental laboratories relied upon modified EPA methods or in-house laboratory standard operating procedures to analyze PFAS in non-drinking water matrices.

Draft EPA Method 1633 is a single laboratory validated method that provides a standardized approach for measuring up to 40 PFAS in a diverse range of environmental matrices including: wastewater, surface water, groundwater, soil, biosolids, sediment, landfill leachate, and fish tissue. This draft method recognizes and incorporates the use of isotope dilution techniques to accurately quantify target PFAS.

Key differences between the draft US EPA Method 1633 and current Bureau Veritas standard operating procedures (based on modified US EPA Methods 537.1 and 533) are highlighted in Table 1 (below). Currently, draft Method 1633 has only been validated by one laboratory. US EPA indicates that a multi-laboratory validation study of draft Method 1633 has begun, and anticipates completion of the study in 2022.

Detailed parameter lists reported are provided in Table 2.

Table 1: Method Comparison between Draft US EPA Method 1633 and Bureau Veritas Standard Operating Procedure CAM SOP-00894/16 (based on a modified US EPA Methods 537.1 and 533.1)

Method Element Bureau Veritas
CAM SOP-00894/16
EPA Method 1633
Scope • Water (incl. drinking water)
• Wastewater
• Soil
• Tissue
• AFFF
• Wastewater
• Surface water
• Groundwater
• Landfill leachate
• Soil
• Sediment
• Biosolids
• Tissue
Sample Collection Water: 3 x 125 mL HDPE bottles per sample (allowance for QC)
Soil: 250mL HDPE jar
Tissue: HDPE jar or LDPE zipper sealed bag (size dependent on sample)
Water: 2 x 500 mL HDPE bottles (per sample)
Soil: 500mL HDPE jar; ≤¾ full
Tissue: Whole fish, cleaned, filleted or other tissue
Allowable sample containers:
- HDPE jar (size dependent on sample)
- LDPE zip bag
- Wrapped in aluminum foil
Sample Storage and Hold Time Water: 28 days (at 4° C)
Soil: 28 days (at 4° C)
Tissue: 28 days (at 4° C)
Extracts: 28 days (at 4° C)
Water: 28 days (frozen at -20° C) 7 days (4° C)
Soil: 90 days (frozen at -20° C)
Tissue: 90 days (frozen at -20° C)
Extracts: 90 days (at 4° C)
Sample Processing All samples spiked with isotopically labeled PFAS analogues prior to processing
Aqueous:
• 125 mL (whole bottle)
• pH adjusted to 4-5
Solids:
• 4g sample size
• Single stage extraction
- 70/30 Methanol/Water (0.5% ammonium hydroxide)
Tissue:
• 4g tissue homogenate
• Single stage extraction
- 0.01M KOH/Methanol
All samples spiked with isotopically labeled PFAS analogues prior to processing
Aqueous:
• 500 mL (whole bottle)
• Percent solids determined by filtration of second bottle.
• pH adjust to 6.5 ± 0.5
Solids:
• 5g sample size
• Three stage extraction
- 10 mL 0.3% methanolic NH4OH
- 15 mL 0.3% methanolic NH4OH
- 5 mL 0.3% methanolic NH4OH
Tissue:
• 2g tissue homogenate
• Three stage extraction
- 0.05M KOH/Methanol
- Acetonitrile
- 0.05M KOH/Methanol NH4OH
Extraction Solid Phase Extraction (SPE):
• Weak anion-exchange (WAX) solid phase extraction
• Extract treated with activated carbon cartridge
Solid Phase Extraction (SPE):
• Weak anion-exchange (WAX) solid phase extraction
• Concentrated acetic acid and activated carbon added to extract
• Extract filtered prior to analysis
Sample Analysis Reverse phase LC-MS/MS Reverse phase LC-MS/MS
Parameters reported 32 compounds 40 compounds
Typical Reporting Limits Aqueous: 2.0 – 100 ng/L
Solids: 0.1 – 5.0 ug/kg
AFFF: 0.80 – 50 ug/L
Aqueous: 1.6 – 40 ng/L
Solids: 0.2 – 5.0 ug/kg
Tissue: 0.5 – 12.5 ug/kg
Year Published 2020 (ver. 16) 2021 (DRAFT)

Notes: Reporting Limit data for US EPA Method 1633 are derived from a single-laboratory validation study and are only provided as examples in this draft method. These will be updated with the pooled reporting limit data from the interlaboratory study results in a subsequent revision.

Table 2: Detailed Parameter Comparison between US EPA Method 1633 and Bureau Veritas Standard Operation Procedure CAM SOP-00894/16 (based on a modified US EPA Method 533.1)

Parameter Abbreviation Bureau Veritas
CAM SOP-00894/16
US EPA Method 1633
Perfluorobutanoic acid PFBA
Perfluoropentanoic acid PFPeA
Perfluorohexanoic acid PFHxA
Perfluoroheptanoic acid PFHpA
Perfluorooctanoic acid PFOA
Perfluorononanoic acid PFNA
Perfluorodecanoic acid PFDA
Perfluoroundecanoic acid PFUnA
Perfluorododecanoic acid PFDoA
Perfluorotridecanoic acid PFTrDA
Perfluorotetradecanoic acid PFTeDA
Perfluorobutanesulfonic acid PFBS
Perfluoropentanesulfonic acid PFPeS
Perfluorohexanesulfonic acid PFHxS
Perfluoroheptanesulfonic acid PFHpS
Perfluorooctanesulfonic acid PFOS
Perfluorononanesulfonic acid PFNS
Perfluorodecanesulfonic acid PFDS
Perfluorododecanesulfonic acid PFDoS  
Perfluorooctanesulfonamide PFOSA
N-methylperfluorooctanesulfonamide MeFOSA
N-ethylperfluorooctanesulfonamide EtFOSA
N-methylperfluorooctanesulfonamidoethanol MeFOSE
N-ethylperfluorooctanesulfonamidoethanol EtFOSE
N-methylperfluorooctanesulfonamidoacetic acid MeFOSAA
N-ethylperfluorooctanesulfonamidoacetic acid EtFOSAA
4:2 Fluorotelomersulfonic acid 4:2FTS
6:2 Fluorotelomersulfonic acid 6:2FTS
8:2 Fluorotelomersulfonic acid 8:2FTS
Hexafluoropropylene oxide dimer acid (GenX) HFPO-DA
4,8-dioxa-3H-perfluorononanoic acid ADONA
9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid 1 9Cl-PF3ONS
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid 2 11Cl-PF3OUdS
Perfluoro-3-methoxypropanoic acid PFMPA  
Perfluoro-3-methoxybutanoic acid PFMBA  
Nonafluoro-3,6-dioxaheptanoic acid NFDHA  
Perfluoro(2-ethoxyethane)sulfonic acid PFEESA  
3-Perfluoropropyl propanoic acid 3:3FTCA  
5:3 Perfluorooctanoic acid 5:3FTCA  
3-Perfluoroheptyl propanoic acid 7:3FTCA