The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

PFAS NON-TARGETED ANALYSIS AND
METHODS INTERIM REPORT #8
Process and Non-Process Wastewater and StormwaterPrepared by
The Chemours Company FC, LLC
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

December 22, 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

TABLE OF CONTENTS
1INTRODUCTION ...............................................................................................................12

INVESTIGATION OF THE SECOND SET OF FIVE MOST ABUNDANTUNKNOWN PFAS IN GENERAL FACILITY DISCHARGE SAMPLES .......................33INVESTIGATION OF THE FIVE MOST ABUNDANT UNKNOWN PFAS IN
CHEMOURS PROCESS WASTEWATER SAMPLES .....................................................44SUMMARY AND NEXT STEPS .......................................................................................45REFERENCES ....................................................................................................................6ii

22 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

LIST OF TABLES
Table 1:

Status of Unknown PFAS - Interim Report #8

LIST OF FIGURES
Figure 1:

Retention Times and Mass Spectra for Unknown C8HF15O8 (in Sample fromLocation 42) and PFO6TeA Standard

Figure 2:

Tandem Mass Spectra for Unknown C8HF15O8 (in Sample from Location 42) andPFO6TeA Standard

Figure 3:

Retention Times and Mass Spectra for Unknown C8H2F14O7S (in Sample fromLocation 16) and RHDA Standard

Figure 4:

Tandem Mass Spectra for Unknown C8H2F14O7S (in Sample from Location 16) andRHDA Standard

ACRONYMS AND ABBREVIATIONS
Chemours

The Chemours Company FC, LLC

DA

diadduct

Facility

Chemours Fayetteville Works, North Carolina

LCliquid chromatography

PFAS

per- and polyfluoroalkyl substances

PFO6TeApentadecafluoro-2,4,6,8,12-hexaoxatetradecan-14-oic acidRHDA

RSU/HFPO Diadduct

QToFquadrupole time-of-flight

TFA

trifluoroacetateiii

22 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

1INTRODUCTION

This interim report has been prepared by The Chemours Company FC, LLC (Chemours) to provide
an update on the characterization of previously unidentified per- and polyfluoroalkyl substances(PFAS) in aqueous samples collected from process wastewater, non-process wastewater (i.e., noncontact cooling water) and stormwater at the Chemours Fayetteville Works, North Carolina site(the Facility). This work is being conducted pursuant to Paragraph 11 subpart (a) in the Consent
Order executed 25 February 2019 between Chemours and the North Carolina Department ofEnvironmental Quality with the Cape Fear River Watch as intervenor. The overall purpose of thisprogram is to identify previously unknown PFAS that may be present in samples of collected waterand to develop standards and methods to facilitate the quantitative analysis of these PFAS, asdescribed in the PFAS Non-Targeted Analysis and Methods Development Plan, Version 2(Chemours and Geosyntec, 2019). This is the 8th interim report.
The samples assessed via the non-targeted program were divided into two categories:••

General Facility Discharge Samples - samples of stormwater, treated non-Chemours
process wastewater and/or non-contact cooling water discharging to the Cape Fear River.
These samples were collected at five locations; andChemours Process Wastewater Samples - samples of process wastewater from Chemours
manufacturing areas. These samples were collected at two locations.

Samples were analyzed by liquid chromatography (LC) coupled to high-resolution quadrupole
time-of-flight (QToF) mass spectrometry (Chemours, 2020a). Unknown PFAS were assigned atentative empirical formula (defined as the number of atoms present in a compound but not thearrangement of the atoms) from unidentified chromatographic peaks with a signal-to-noise level
greater than six and using the atomic mass defect of fluorine as the molecular feature. An atomic
mass defect refers to the phenomenon that the mass of an atom is not exactly equal to the numberof subatomic particles (protons and neutrons) or the atomic mass number (except for carbon-12 bydefinition) due to differences in mass lost (as energy) when the atomic nucleus is formed for eachisotope. Fluorine is well-known to have a negative mass defect, where the exact mass is slightly
less than the mass number. When the QToF mass spectrometer is operated in the negative mode,
one can select fluorine-containing features and empirical formulas using available software
provided by the instrument vendor.
The analysis identified 21 potentially unknown PFAS present in General Facility Discharge
samples and 250 potentially unknown PFAS present in Chemours Process Wastewater samples,with a total of 257 potential unique unknown PFAS (14 unknown PFAS were present in both typesof samples). Two of the unknown PFAS were later identified as TFA and HFPO Trimer Acid, andnot carried forward further in the non-targeted analysis program. Empirical formulas weredetermined for all unknown PFAS. This work represented the first part of the Initial Assessment
step in the Development Plan. The second part of the Development Plan, the Enhanced Assessment
122 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

is to develop tentative molecular structures and subsequently, for the highest priority detectedsamples, develop authentic standards (i.e., synthesize samples of the compounds to facilitate
traditional targeted analysis). To prioritize developing authentic standards for the most abundantunknown PFAS for each grouping of samples (General Facility Discharge and Chemours ProcessWastewater), the 5 most abundant unknown PFAS from each group were advanced to theEnhanced Assessment step. As each group of 5 unknown PFAS from each group is resolved, thenext group of 5 will be advanced to the Initial Assessment step. The status of the unknown PFAS
in each group prior to this report is provided below; further details are provided in the references(Chemours, 2020a, 2020b, 2021a, 2021b, 2022a, 2022b, 2023).
General Facility Discharge Samples
The 5 most abundant unknown PFAS from the General Facility Discharge samples were identified
as sodium or potassium adducts of acetate clusters; these are formed in the MS source from sodium
or potassium present in the sample matrix and acetate from the LC eluent buffer and are not PFAS.
The next group of 5 unknown PFAS is currently under investigation.
The status of the 10 most abundant unknown PFAS in the General Facility Discharge samples
prior to this report was:••••seven (GFD-1, -2, -3, -4, -5, -9 and -10) were identified as sodium or potassium adducts ofacetate clusters. These are formed in the mass spectrometer source from sodium orpotassium present in the sample matrix and acetate or sulfate present in the LC eluent
buffer. The incorrect empirical formulas (containing fluorine) were generated by thecomputer algorithm used to determine empirical formulas and were mistakenly flagged asfluorinated compounds (Chemours, 2021a). These compounds are not PFAS and theproposed empirical formulas have been revised showing the absence of fluorine;one (GFD-6) has a proposed molecular structure, and a commercial standard for theproposed molecular structure is available. The commercial standard has been purchased by
Chemours and has undergone purification by Chemours so that accurate assessment of theC8HF15O8 peak can be undertaken.
one (GFD-7) was identified as the sodium salt of a TFA acetate adduct; andone (GFD-8) was identified as R-EVE, which is a known PFAS associated with theFacility.

Chemours Process Wastewater Samples
The status of the 5 most abundant unknown PFAS in the Chemours Process Wastewater samples
prior to this report was:222 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306••••

one (CPWW-1) was identified as potentially being present in one of the production
processes at the Facility. Samples from the production process have been obtained fromthe Facility and have been purified to isolate the production PFAS at sufficient purity thatit can be used as a standard;one (CPWW-2) was identified as EVE Acid, which is a known PFAS associated with theFacility;
one (CPWW-3) was identified as an unknown PFAS, and a molecular structure has not yet
been proposed; andtwo (CPWW-4 and -5) were identified as unknown PFAS, and molecular structures havebeen proposed.

The remainder of this 8th interim report consists of:•••2

Section 2: Investigation of the Second Set of Five Most Abundant Unknown PFAS inGeneral Facility Discharge Samples
Section 3: Investigation of the Five Most Abundant Unknown PFAS in Chemours Process
Wastewater Samples; andSection 4: Summary and Next Steps.

INVESTIGATION OF THE SECOND SET OF FIVE MOST ABUNDANTUNKNOWN PFAS IN GENERAL FACILITY DISCHARGE SAMPLES

The peak corresponding to C8HF15O8 (GFD-6) in General Facility Discharge samples was assessedagainst the commercial standard (pentadecafluoro-2,4,6,8,12-hexaoxatetradecan-14-oic acid(PFO6TeA)) corresponding to the structure proposed for C8HF15O8 (CF3-O-CF2-O-CF2-O-CF2-OCF2-O-CF2-O-CF2-COOH). Results showed that:•••the retention times of the peaks on the liquid chromatograph were identical (Figure 1);
the mass spectra of the peaks were identical (Figure 1); andthe fragmentation patterns of the largest ion (with a mass-to-charge ratio of 508.93) in themass spectra were identical (Figure 2).

The peak corresponding to C8HF15O8 in General Facility Discharge samples was consequently
concluded to be PFO6TeA.
The current status of the second set of 5 most abundant PFAS in the General Facility Dischargesamples (as well as of the first set of 5 most abundant PFAS) is summarized in Table 1.

3

22 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

3INVESTIGATION OF THE FIVE MOST ABUNDANT UNKNOWN PFAS INCHEMOURS PROCESS WASTEWATER SAMPLES

The most abundant unknown PFAS in the Chemours Process Wastewater samples (CPWW-1;
C8H2F14O7S) had the proposed structure of CF3-CF(COOH)-O-CF2-CF(CF3)-O-CF2-CF2-SO3H
which was identified as an intermediate product, RSU/HFPO Diadduct (RHDA), in one of theproduction processes at the Facility. RHDA was isolated from a production sample and the peakcorresponding to CPWW-1 in Chemours Process Wastewater samples was then assessed against
this RHDA standard.
Results showed that:•••the retention times of the peaks on the liquid chromatograph were identical (Figure 3);
the mass spectra of the peaks were identical (Figure 3); andthe fragmentation patterns of the largest ion (with a mass-to-charge ratio of 506.92) in themass spectra were identical (Figure 2).

The peak corresponding to CPWW-1 in Chemours Process Wastewater samples was consequently
concluded to be the RHDA salt.
The current status of the 5 most abundant PFAS in the Chemours Process Wastewater samples issummarized in Table 1.

4SUMMARY AND NEXT STEPS

A summary of results to date and the next steps for the potential unknown PFAS in General Facility
Discharge and Chemours Process Wastewater samples is provided below and in Table 1.
General Facility Discharge Samples
The current status of the 10 most abundant unknown PFAS in the General Facility Discharge
samples is:••seven (GFD-1, -2, -3, -4, -5, -9 and -10) were identified as sodium or potassium adducts ofacetate clusters. These are formed in the mass spectrometer source from sodium or
potassium present in the sample matrix and acetate or sulfate present in the LC eluent
buffer. The incorrect empirical formulas (containing fluorine) were generated by thecomputer algorithm used to determine empirical formulas and were mistakenly flagged asfluorinated compounds (Chemours, 2021a). These compounds are not PFAS and theproposed empirical formulas have been revised showing the absence of fluorine;one (GFD- 6) was identified as PFO6TeA by comparison to a recently available commercial
standard (this report);
4

22 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306••

one (GFD-7) was identified as the sodium salt of a TFA acetate adduct. TFA is a known
PFAS associated with the Facility; andone (GFD-8) was identified as R-EVE, which is a known PFAS associated with theFacility.

Of the 10 most abundant unknowns in the General Facility Discharge samples, 9 have been shownto not be PFAS or to be previously known PFAS. The tenth has been shown to be PFO6TeA, forwhich an authentic standard is available. The next step for PFO6TeA, according to the Workplan(Chemours and Geosyntec Consultants, 2019), is to develop a test method. PFO6TeA will beanalyzed using existing test methods to assess if it can be adequately separated and accurately
quantified in the presence of other Table 3+ PFAS. If not, additional test methods will bedeveloped. A method detection limit study will be conducted to establish a reporting limit and amatrix interference study will be conducted to assess the quantification of PFO6TeA inenvironmental matrices related to the Facility.
Additionally, Chemours will begin work on identifying the molecular structures of the third set offive most abundant unknown PFAS (GFD-11 through -15) in the General Facility Discharge
samples.
Chemours Process Wastewater Samples
The current status of the 5 most abundant unknown PFAS in the Chemours Process Wastewater
samples is:••••one (CPWW-1) was identified as RHDA by comparison to a standard purified fromproduction samples (this report);one (CPWW-2) was identified as EVE Acid, which is a known PFAS associated with theFacility;
one (CPWW-3) was identified as a potential unknown PFAS, and a molecular structure has
not yet been proposed; andtwo (CPWW-4 and -5) were identified as potential unknown PFAS, and molecular
structures have been proposed.

The next step for the Chemours Process Wastewater samples to develop a synthetic pathway for
RHDA so that an authentic standard can be produced. The production of an authentic RHDA
standard will likely take several months, after which a test method can be developed (as describedabove for PFO6TeA).
Additionally, Chemours will continue to develop a molecular structure for CPWW-3 (so that asynthetic pathway can be developed), and to develop synthetic pathways for CPWW-4 and -5 (sothat authentic standards can be produced). Note that the synthetic pathways are challenging, andthis process may take considerable time to complete given the complex structure of these
522 December 2023

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

compounds. Chemours will also begin work on identifying the molecular structures of the second
set of five most abundant unknown PFAS (CPWW-6 through -10) in the Chemours Process
Wastewater samples.

5REFERENCES

Chemours, 2023. PFAS Non-Targeted Analysis and Methods Interim Report #7. June 30, 2023.
Chemours, 2022a. PFAS Non-Targeted Analysis and Methods Interim Report #5. June 30, 2022.
Chemours, 2022b. PFAS Non-Targeted Analysis and Methods Interim Report #6. December 30,2022.
Chemours, 2021a. PFAS Non-Targeted Analysis and Methods Interim Report #3. July 30, 2021.
Chemours, 2021b. PFAS Non-Targeted Analysis and Methods Interim Report #4. December 22,2021.
Chemours, 2020a. PFAS Non-Targeted Analysis and Methods Interim Report. June 30, 2020.
Chemours, 2020b. PFAS Non-Targeted Analysis and Methods Interim Report #2. December 31,
2020.
Chemours and Geosyntec Consultants, 2019. PFAS Non-Targeted Analysis and Methods
Development Plan. Version 2. December 5, 2019.

622 December 2023

TABLE 1
STATUS OF UNKNOWN PFAS - INTERIM REPORT #8
Chemours Fayetteville Works, North Carolina

SampleSourceGeneral Facility
Discharge

Chemours
Process
Wastewater

Rank(by IonAbundance inSample Source)

Mass(Da)

Mass toCharge Ratio(m/z)

Tentative

Revised

GFD-1

142.0241141.0168

C4H5F3O2*

C4H7O4Na

GFD-2

157.9983

156.9910

C4H2F4O2*

C4 H6 O4 K

GFD-3

224.0272

223.0199

C6H6F6O2*

C6H10O6Na2GFD-4306.0302

305.0230

C8H7F9O2*

C8H13O8Na3

GFD-5388.0331

387.0258

C10H8F12O2*

C10H16O10Na4

GFD-6509.9432

508.9357

C8HF15O8--

Structure identified as pentadecafluoro-2,4,6,8,12-hexaoxatetradecan-14oic acid by comparison to authentic standard.

None

GFD-7

195.9956

194.9884

C4H2F6O2*

C4H4F3O4Na

Structure identified as sodium salt of TFA and acetate adduct.
Correct formula is C4H4F3O4Na

None

GFD-8407.9670

406.9596

C8HF13O4--

Identified as R-EVE

None

GFD-9283.9544

282.9471

C4HF9O2S*

C4H7SO8Na3Structure identified as sodium salt of sulfuric acid and acetate
dimer adduct. Correct formula is C4H7SO8Na3. This compound isnot a PFAS.

None

GFD-10240.0010

238.9937

C6H3F7O2*

C6H10O6NaKStructure identified as sodium and potassium salt of acetate dimer.
Correct formula is C6H10O6NaK. This compound is not a PFAS.

None

CPWW-1507.9302

506.9229

C8H2F14O7S--

Structure identified as a production intermediate, RSU/HFPO Diadduct,by comparison to authentic standard.

Develop a synthetic pathway for RSU/HFPO Diadduct so that standard solutions can becreated.

CPWW-2407.9670

406.9598

C8HF13O4--

Identified as EVE AcidNone

CPWW-3475.9587

474.9515

C8H5F13O6S--

No proposed molecular structure yetContinue to develop a proposed molecular structure.

CPWW-4471.9630

470.9556

C9H2F14O6--

HOOC-CF2-CF2-O-CF(CF3)-CF2-O-CF(CF3)-COOH

Synthesis of an authentic standard is under consideration.

CPWW-5345.9693

344.9620

C6HF11O4--

CF3-O-CF2-O-CF2-CF2-CF2-COOH

Synthesis of an authentic standard is under consideration.

Empirical Formula
Proposed Molecular Structure

Structures identified as sodium or potassium adducts of acetateclusters; these are formed in the MS source from sodium orpotassium present in the sample matrix and acetate from the LC
eluent buffer.

Next Step For Identification of Unknown

None

Compounds are not PFAS.

Notes:* - tentative empirical formula has been revised following further investigation-- - revised empirical formula not required
adduct - a product of a direct addition of two or more distinct molecules resulting in a single reaction product containing all atoms of all components- further investigation into identification of unknown not required
C - carbon
LC - liquid chromatograph
Da - dalton
MS - mass spectrometerF - fluorine
O - oxygen
H - hydrogen
PFAS - per- and polyfluoroalkyl substances
S - sulfur

December 2023

Standard (PFO6TeA) peak: retention time = 12.2 minutes

Retention times match
Unknown (C8HF15O8) peak: retention time = 12.2 minutes

Standard (PFO6TeA) mass spectrum

Mass spectra match
Unknown (C8HF15O8) mass spectrum

Notes:EIC - extracted ion chromatogram
PFO6TeA - pentadecafluoro-2,4,6,8,12-hexaoxatetradecan-14-oic acid

Retention Times and Mass Spectra for Unknown C8HF15O8 (inSample from Location 42) and PFO6TeA Standard
Chemours Fayetteville Works, North Carolina

FigureDecember 2023

1Standard (PFO6TeA) MS/MS of precursor ion with m/z 509.9343

MS/MS spectrum match
Unknown (C8HF15O8) MS/MS of precursor ion with m/z 509.9343

Notes:EIC - extracted ion chromatogram for mass-to-charge ratio of 508.9343
m/z - mass to charge ratioPFO6TeA - pentadecafluoro-2,4,6,8,12-hexaoxatetradecan-14-oic acid

Tandem Mass Spectra for Unknown C8HF15O8 (in Sample fromLocation 42) and PFO6TeA Standard
Chemours Fayetteville Works, North Carolina

FigureDecember 2023

2Standard (RHDA salt) peak

Retention times match
Unknown (C8H2F14O7S) peakStandard (RHDA) mass spectrum

Mass spectra match
Unknown (C8H2F14O7S) mass spectrum

Notes:EIC - extracted ion chromatogram
RHDA - RSU/HFPO Diadduct

Retention Times and Mass Spectra for Unknown C8H2F14O7S(in Sample from Location 16) and RHDA Standard
Chemours Fayetteville Works, North Carolina

FigureDecember 2023

3Standard (RHDA) MS/MS of precursor ion with m/z 506.9235

MS/MS spectra match
Unknown (C8H2F14O7S) MS/MS of precursor ion with m/z 506.9235

Notes:EIC - extracted ion chromatogram for mass-to-charge ratio of 508.9343
m/z - mass to charge ratio
RHDA - RSU/HFPO Diadduct

Tandem Mass Spectra for Unknown C8H2F14O7S (in Sample
from Location 16) and RHDA Standard
Chemours Fayetteville Works, North Carolina

FigureDecember 2023

4