WAIT-CBI-2021.02.23_CCO.p26_Dr.SusanRichardsonLetterToNCDEQReDeadlineExtension

February 23, 2021

Sheila C. Holman
Assistant Secretary for the Environment
NC Department of Environmental Quality
1601 Mail Service Center
Raleigh, NC 27699

Re: Additional information requested per the 6-month extension request

Dear Ms. Holman,

I was forwarded a message that you needed the following information in regard to my request for
a 6 month extension of our project, ‘Development of a Total Organic Fluorine (TOF) Method for
the Analysis of Process Wastewater Streams and Air from Fayetteville Works (NC)’, to
December 31, 2021.

• More updated information on progress made to date;
• A schedule and timeline of actions to be taken between now and Dec 31.

As mentioned in my previous letter, the continuing covid pandemic has limited our capacity in
the laboratory, also including not receiving research supplies on a timely basis. We are providing
below more updated information on our progress and a schedule and timeline of actions we will
take between now and December 31. Please note that some of the information being provided is
considered to be R&D proprietary. We can provide further details if needed.

More Information on Progress
Since the last progress report on December 20, 2020, our research focus has been primarily on
pushing to finish optimizing the Absorbable Organic Fluorine (AOF) extraction method. A large
part of this push has focused on ensuring that the final method can reliably remove higher levels
of inorganic fluorine that may be present in real environmental samples. We recently learned that
the concentration of inorganic fluorine present may be much higher than what current
experiments for AOF optimization have shown the capability to remove. We have also found
that some PFAS standards can also contain inorganic fluorine, which can result in falsely high
percent recoveries of organic fluorine during method optimization experiments, making it
difficult to reliably distinguish between inorganic and organic fluorine for optimization. Our
current focus is placed on receiving new PFAS standards and conducting several experiments
with the goal of removing higher concentrations of inorganic fluorine in samples.

Current Progress to Date: AOF Activated Carbon (AC) Extraction
Optimization of IC instrument methods for optimal fluoride sensitivity and separation (column
selection, eluent conditions, sample volume injection, etc.)
System and method background analysis for inorganic fluorine
pH adjustment of sample before extraction
Activated carbo (AC) composition
Number of AC columns needed
Varying rinsing solutions as well as a sample pretreatment step to remove inorganic fluorine
have been tested
Volume of aqueous absorption solution
Composition and pH of aqueous absorption solution
Combustion time

Parameters Left to Optimize: AOF AC Extraction
Sample holding time
Sample volume (potential for dilution)
Volume of rinsing solution
Combustion temperature

Current Progress to Date: Extractable Organic Fluorine (EOF) Solid Phase Extraction
(SPE)
Optimization of ion chromatography (IC) conditions for optimal fluoride sensitivity and
separation as stated in above AOF method
Several different SPE phases have been purchased including a new phase not listed in the
original proposal
Phases have been compared for their ability to rinse and not retain inorganic fluorine
Experiments for optimizing elution steps have begun
Composition and pH of absorption solution

Parameters Left to Optimize: EOF SPE
Sample holding time
pH of sample before extraction
Volume of sample/whether to dilute
SPE phases will be compared later on using various parameters to help pick the best suited
phase
SPE elution conditions will continue to be optimized
Temperature and time of combustion will be re-evaluated for quartz wool combustion, but is
expected to be similar to the AOF method

ANTICIPATED (QUARTERLY) MILESTONES:
March 31, 2021: Evaluation of AOF sample volume (dilution), rinsing solution volume and
composition, and inorganic fluorine removal from samples
June 31, 2021: Evaluation of SPE sample pH, sample volumes, elution conditions, and
combustion time and temperature
September 30, 2021: Evaluation of sample holding times and temperature for both AOF and
EOF methods and comparison of methods with UPLC-MS/MS analysis of known standards
December 31, 2021: Final report for optimized method

Please let us know if the extension request is acceptable.

Sincerely,

Susan D. Richardson, Ph.D.
Arthur S. Williams Professor of Chemistry
Department of Chemistry and Biochemistry
University of South Carolina