US EPA SW-846 Validated Method 8327 Per- and Polyfluoroalkyl Substances (PFAS) Using External Standard Calibration and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)


US EPA SW-846 Validated Method 8327
Per- and Polyfluoroalkyl Substances (PFAS) Using External Standard Calibration and Liquid
Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Executive Summary
EPA has validated SW-846 Method 8327: Per- and Polyfluoroalkyl Substances (PFAS) Using
External Standard Calibration and Liquid Chromatography/Tandem Mass Spectrometry
(LC/MS/MS) in a two-phase study for 24 PFAS analytes and 19 isotopically-labeled PFAS
surrogates in four aqueous matrices of reagent water, surface water, groundwater, and
wastewater effluent, three of which were intended to represent non-potable water matrices. The
PFAS targets included sulfonic acids (e.g., PFOS), carboxylic acids (e.g., PFOA), fluorotelomer
sulfonic acids (e.g., 6:2 fluorotelomer sulfonate, or FTS), and sulfonamides and
sulfonamidoacetic acids (e.g., N-MeFOSAA).
The Statistical Analysis Report for SW-846 Method 8327 Multi-Lab Validation Study (June
2019) (Statistical Report) analyzes the study results for bias using percent (%) recovery and for
precision using the relative standard deviation (RSD) of target analyte concentrations, which the
study measured in the four aqueous matrices prepared at 60 and 200 nanograms/liter (ng/L)
(parts per trillion) spiking levels. The Statistical Report contains additional analyses of study
results for performance per media, per concentration level, and per laboratory.
The US EPA SW-846 Method 8327 Multi-Laboratory Validation Study Quality Control
Summary Report (June 2019) (Data Validation Summary) summarizes the quality control
(QC) results from the multi-laboratory validation of Method 8327 using the dilution preparation
method in Appendix B of Method 8327. EPA evaluated data from 12 laboratories for compliance
with the study instructions, method, and overall usability (i.e., for instrument calibration and for
study sample preparation and analysis). EPA excluded data from four laboratories for not
following the specified protocols (more detail about the basis used for exclusion of each
laboratory's data is provided in Appendix E of the Statistical Report). For the remaining eight
laboratories, EPA reviewed data for completeness and validated data using criteria provided in
the method and study instructions.
The Statistical Report and Data Validation Summary showed more bias and/or less robust
measurement precision for the longer-chain carboxylic acids, the amidoacetic acids, the
fluorotelomer sulfonic acids, and perfluorobutanoic acid. The performance for 6:2 fluorotelomer
sulfonate (6:2 FTS) was erratic, with high average recovery and high RSDs in some matrices and
spike levels. Multiple laboratories reported high or variable background levels of this chemical,
including in method blanks and calibration standards. A summary of study sample results is
provided below for the 24 PFAS analytes and two spiking levels across all four aqueous matrices
(Table 1).
With the exception of 6:2 FTS, the target analytes in the study generally met the precision and
bias criteria defined in the method and study instructions. The principal problems laboratories
encountered with preparation and analysis of study samples were retention of the target analytes

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and surrogates in solution (particularly when stored in glass containers), background
contamination, and instrument sensitivity.
EPA revised draft Method 8327 to address the precision and bias problems observed in the study
data by adding several cautions, particularly for the longer chain PFAS carboxylic acids and
amidoacetic acids, including:
•	ensuring that the composition of the stock and intermediate standards contain enough
organic cosolvent (> 95%);
•	avoiding storage in glass containers; and
•	avoiding subsampling prior to adding a sufficient proportion of organic cosolvent.
Considering the issues observed with multiple QC failures in the validation study as described
above, EPA also added a general caution for 6:2 FTS.
Based on the Statistical Report and Data Validation Summary, EPA deems draft SW-46 Method
8327 generally acceptable. According to the SW-846 method publication process, EPA is posting
the draft validated method and supporting materials for a 30-day public comment period. After
the public comment period closes, EPA will adjudicate comments and revise the method
accordingly before finalizing it and incorporating it into the Test Methods for Evaluating Solid
Waste: Physical/Chemical Methods compendium.

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Table 1. Summary of bias (as % recovery)1 and precision (as % RSD) of target analyte concentrations in study samples, across four matrices and eight
laboratories
Target Analyte
Prepared concentration: 60 ng/L (nom.; n=159)
Prepared concentration: 200 ng/L (nom.; n=160)
Average
(Mean) %
Recovery
Median %
Recovery
% RSD
% measured within
70-130% of
prepared conc.
Average
(Mean) %
recovery
Median %
Recovery
% RSD
% measured within
70-130% of
prepared conc.
PFTeDA
89.5
90.1
27.3
73.6
95.0
93.1
18.3
90.0
PFTrDA
95.7
93.9
25.2
79.9
99.8
99.0
18.2
87.5
PFDoA
95.8
91.7
25.2
81.1
102
98.5
18.0
89.4
PFUdA
97.3
94.4
18.9
90.6
104
101
16.1
91.3
PFDA
99.4
97.0
18.8
92.5
104
102
12.7
96.9
PFNA
96.8
96.1
14.3
96.9
102
102.2
11.4
99.4
PFOA
99.9
99.4
13.9
97.5
103
103
10.6
98.8
PFHpA
97.9
95.9
13.3
98.7
100
99.2
9.2
99.4
PFHxA
97.2
94.9
18.4
91.2
98.5
97.0
11.2
98.8
PFPeA
107
103
24.7
91.2
100
98.8
12.6
100
PFBA
93.6
91.3
24.1
80.5
94.8
93.7
17.5
90.0
PFDS
95.7
93.2
20.4
86.8
100
98.5
17.6
91.3
PFNS
100
99.7
17.8
89.3
106
103
13.9
93.8
PFOS
104
100
17.8
89.3
108
104
27.9
96.9
PFHpS
98.9
97.7
14.2
96.9
102
102
10.2
98.8
PFHxS
97.2
97.5
15.9
93.1
102
99.8
10.5
98.8
PFPeS
96.0
95.1
10.8
98.1
99.3
97.8
00
00
99.4
PFBS
96.7
94.7
14.4
96.2
99.8
98.4
ii.i
98.8
FOSA
88.7
88.1
14.1
92.5
95.5
94.2
10.6
99.4
8:2 FTS
103
99.9
20.1
87.4
110
108
16.1
87.5
6:2 FTS
95.0
84.7
191.7
61.0
92.4
94.6
51.8
66.9
4:2 FTS
95.1
91.8
19.7
86.8
102
99.9
14.4
96.3
NEtFOSAA
99.3
96.0
26.4
83.6
107
99.1
20.1
85.6
NMeFOSAA
98.2
94.9
22.7
89.3
102
98.5
16.6
91.9
1 Note: Recoveries were calculated from concentrations in field samples after correcting for background, which was accomplished by subtracting the
average unspiked matrix concentration reported by the same laboratory (n=5). Correction for background was not performed for average unspiked
matrix concentrations < 5 ng/L. Refer to the Statistical Report, Data Validation Summary, or Method 8327 for definitions of analyte abbreviations.

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