Page 1 of 5 **Responses to EPA Review of Fluoropolymer s**  **Incineration ECA Final Study Report**

**- Part 2**  M arch 2, 2015

On July 12, 2013, Dr. Philip Taylor of the University of Dayton Research Institute (UDRI) responded to several questions sent via electronic mail on May 20, 2013 by Joe Avcin of EPA. Three areas or sub

- areas of inquiry were deferred to a later date. Further work on the se three items has been delayed primarily due to refocusing resources on completing and publishing a paper in Chemosphere on t he Telomers ECA incineration study in 2014 and Dr. Taylor’s retirement from UDRI. The text below responds to each of the remaining three items. It is important to note that b oth Phase I and Phase II t esting described in the Final Study Report were perfor med in accordance with the requirements of the Enforceable Consent Agreement (ECA) and TSCA GLPs as embodied in the EPA

- approved Quality Assurance Project Plans (QAPPs). The project team established and executed a quality management system to assure confo rmance with the EPA

- approved QAPPs and documented such conformance in the F inal Study Report submitted October 30, 2009

.

1

. Area #3

– O

- ring a source of F? During Composite 2 incineration testing of the previously

- completed fluorotelomer Phase II incineration study, unsteady oxygen and carbon dioxide exhaust concentrations, perhaps due to exhaust gas leaks, led to reactor system repairs. The repairs included replacing corroded stainless steel tubing and replacing the reactor exit

- end sil icone O

- ring with a higher

- temperature

- rated perfluoroelastomer O

- ring. This perfluoroelastomer O

- ring remained in service during all fluoropolymer Phase II incineration testing. EPA would like to better understand if the observed fluoride ion concentrat ions in the impinger samples may be the result of the O

- ring used in the reactor system as well as the combustion of the fluoropolymer composites.

The final report concludes that the fluoride ion concentration resulting from the experimental runs are due entirely to the combustion of the fluoropolymer composites. This conclusion was made with the following statement on page 16 and 17 of the final report: “Fluoride ion analytical results for the pre

- test steam cleanings (in contrast to pre

- test thermal bla nks) indicate that degradation of the perfluoroelastomer O

- ring on the reactor exit is the primary source of fluoride ion in the impingers under post

- run steam cleaning conditions. (These conditions include higher exit end fitting temperature and much high er exhaust gas water concentration than during experimental runs.) Hence, the fluoride ion results for the experimental runs correspond directly to the combustion of the fluoropolymer composites, independent of O

ring degradation during steam cleaning.”

E PA finds a potential issue with using a perfluoroelastomer O

- ring as a corrective action to repair a leak in the exhaust gas line and with concluding that its use had no effect on the results for experimental runs. The impinger results for the thermal bla nks also contained a detectable concentration of fluoride ion ranging from 0.031 to 0.12 mg/L (approximately ten

- to twenty

- times less than the combustion experimental run results). The contribution of fluoride ion during the thermal blank runs may also b e a result of O

- ring degradation. Therefore, EPA wants to know if it is possible that a portion of the fluoride ion present during the experimental runs may also be a result of O

- ring degradation.

In a related comment as part of Area #5, EPA also state d : Further, the study did not subtract any estimate of baseline fluoride ion levels due to degradation of the O

- ring.

EPA asks about (a) use of a perfluoroelastomer O

- ring as a corrective action to repair a n apparent leak in the reactor exhaust gas line and (b) the potential contribution of perfluoroelastomer O

- ring degradation under experimental run ( and thermal blank ) conditions to fluoride ion results for experimental run impinger samples.Page 2 of 5 a. As the Agency notes, repairs necessary to correct unsteady oxygen and carbon dioxide exhaust concentration during Phase II fluorotelome rs incineration testing included replacing the reactor exit

- end silicone O

- ring with a perfluoroelastomer O

- ring. The se repairs were described in a July 22, 2008 Corrective Action Form (included in Appendix 1 to the Fluorotelomers Final Study Report)

. As the run checklist T4 Nut readings for Fluorotelomer runs 4

- 6 and runs 1R

- 3R in Appendix 26 to the Fluorotelomers Final Study Report indicate, r eactor exit fitting (T4 Nut) temperatures during Fluorotelomers Phase II combustion testing (especially steam cl eaning) exceed ed the maximum continuous service temperature of the exit

- end silicone O

- rin g . T he only commercially available O

- ring material capable of such higher temperature service was and is perfluoroelastomer. Hence, the reactor exit O

- ring was upgr aded to a perfluoroelastomer O

- ring (Kalrez ® 7075) for the remain der of the Fluorotelomers study; see page 111 of Rich ard Striebich ’s Fluorotelomers Phase II notebook in Appendix 5 to the Fluorotelomers Final Study Report. Upgrading to a perfluoroelastomer O

- ring was necessary to assure steady and representative oxygen and carbon dioxide monitoring and to keep the study on schedule to comply with the deadlines imposed by the Fluorotelomers incineration ECA.

As the second July 22, 2008 Corrective Action F orm in Appendix 1 to the Fluorotelomers Final Study Report indicates, additional testing was performed to evaluate the potential contribution of the exit end perfluoroelastomer O

- rings to the impinger fluoride results. These additional tests we re describe d in Appendix 29 to the Fl uorotelomers Final Study Report and indicated that fluoride levels seen in Fluorotelomers study steam cleaning samples were due to perfluoroeleastomer O

- ring degradation during steam c leaning. Analytical laboratory problems durin g analysis of the Fluorotelomers study samples prevented confident low

- level quantitation of fluoride in the HPLC water used to fill the impingers prior to each run, preventing the study team from considering the contribution of the HPLC water to fluoride background during the Fluorotelomers study.

In preparation of the Fluoropolymers incineration study, the reactor exit

- end O

- ring was upgraded from Kalrez® 7075 to Kalrez® 9100 to minimize the potential for perfluoroelastomer O

- ring contribution to impin ger fluoride levels ; see October 7, 2009 Corrective Action form by Richard Striebich (included in Appendix 1 to the Fluoropolymers Final Study Report). As noted in that Corrective Action form, the upgrade to 9100 was to assure less HF off

- gassing at the r eactor exit end fitting based on consultation with the perfluoroelastomer O

- ring manufacturer.

b. The data presented for the series of pretest steam cleanings (prior to use of each new reactor tube ) in the Fluoropolymers Final Study Report clearly show t hat fluoride ion results for steam cleaning samples (with higher fitting temperature and much higher exhaust gas water concentration than experimental runs) during the Fluoropolymers incineration study are attributable to the perfluoroelastomer O

- ring on the exit

- end of the
reactor . However, the potential contribution of the O

- ring to the experimental run and thermal blank impinger sample fluoride results is another matter

.Page 3 of 5 Section F.4

. a(5) of the Fluoropolymers Final Study Report (p. 56) notes that the sources of background levels of fluoride ion in the thermal blank impinger samples were (1) the HPLC water used to fill the impingers prior to each run

, (2) the synthetic air feed to the reactor system, and (3) potential degradation of the exit

- end per fluoroelastomer O

- ring.

(1) Review of Richard Striebich’s Fluoropolymers Phase II notebook (Appendix 36 to the Fluo ropolymers Final Study Report) indicates that Lot C28T002 water was used to fill impingers f or runs 1, 2, and 3, that Lot D14T068 water was used to fill impingers for runs 4, 5, 6, and 7, and that Lot D13U027 water began to be used to fill imping ers at the beginning of run 8. ( Review of the notebook pages does not show clear evidence of actual use of Lot F17U015 water to fill impingers in the test program. ) Fluoride was measured in the HPLC water. Table 16 of the Fluoropolymers Final Study Report indicates that fluoride was not detected in Lots C28T002 and D14T068 and that Lots D13U027 and F17U015 contained 0.037 mg/L and 0.043 mg/L of fluoride ion, respectively.

(2) While fluoride was likely present in commercially prepared synthetic air at the time of this work based on review of Wickbold Torch system blanks at the Total Fluorine analysis laboratory used in another part of the Fluoropolymers study, the synthetic air used in testing at UDRI was not analyzed for fluoride.

(3) For a given duration, polymer thermal degradation increases with increasing temperature. Hence, i f thermal degradation of the perfluoroelastomer O

- ring under thermal blank (and experimental run conditions) were the main contributor to thermal blank fluoride levels, thermal blank fluoride concentrations should positively correlate with O

- ring (T4 nut) temperatures

. However, c omparison of T4 nut temperatures to fluoride levels for the 2 8 thermal blanks samples collected in this study does not reveal a clear trend even if the thermal blank results from Run 8 onward were blank corrected for the fluoride ion concentration of the HPLC water. More recent information indicate s that for conditions at thermal blank (and experimental run) temperatures HF off

- gassing from
two perfluoroelastomer O

- rings (Kalrez® 8900 and Kalrez® 8475) is not expected to be significantly different from HF off

- gassing from silicone (VMQ

- T1) O

- rings ; see Figures 11, 12, and 14 of the enclosed 2009 AVS Symposium technical paper “Outgassing Characterization of Elastomeric Seals Used in Semiconductor Wafer Processing.”

Based on the information provided in points (1), (2), and (3) above, there is not sufficient information available to correct the experimental run impinger fluoride ion results for background fluoride levels. If the experimental run fluoride ion results for Runs 8

- 12 were corrected for the 0.037 mg/L level in the HPLC water used in these runs, the fluoride

r ecoveries from these five runs would decrease from the range of 100% to 120% in Table 18 of the Fluoropolymers Final Study Report to the range of 97% to 116%

. However, blank correction here would not be consistent with the approach used in the data validat ion of the fluoride ion analytical laboratory data package in Appendix 1 to the Fluoropolymers Final Study Report, for the experimental run fluoride ion results are 13 to 22 times higher than the associated thermal blank values.Page 4 of 5 T he variability in the flu oride ion recoveries cannot be thoroughly explained by the factors discussed above. But the range of fluoride ion recoveries for this experimental program (Table 18) is generally consistent with the range of single

- operator mean recoveries for repeat fluo ride determinations by ion chromatography across the aqueous matrices evaluated (73% to 101%) for Method 300.0 ( Table 2A in EPA, 1993) and with the range of fluoride recoveries using the IonPac AS4A

- SC Column (57.0% to 109.0%) across types of water samples (Table 4 in Dionex, 2004).

Literature Cited:

EPA, 1993. Method 300.0: Determination of Inorgan ic Anions by Ion Chromatography, Revision 2.1, August 1993.

Dionex, 2004. Application Note 133: Determination of Inorganic Anions in Drinking Water by Ion Chromatography.

2

. Area #4

– CGA Concerns Issues were encountered during testing that involved the c ontinuous gas analyzer (CGA). During the post

- run thermal blank for the third run, the CGA unexpectedly shutdown and the post

- run thermal blank had to be rerun. As a result of this issue, the CGA was serviced by the manufacturer prior to the seventh set of runs. It is noted in the final report on page 47 that the pressure drop across the CGA decreased to 14 inches W.C. during the final six runs compared to 22 inches W.C. that was observed during the first six runs. It was also noted that the records for the recalibration of the CGA after it was serviced wer e not provided (see Area # 8). It is not clear how this pressure drop may have affected the final results or if it had any effect at all.

Additionally, during part of the ninth post

- run steam cleaning and all of the twelfth post

- run steam cleaning, the CGA was connected to the reactor system exhaust gas. The established proto col was to not have the CGA connected during steam cleanings to prevent condensation from occurring in the tubing of the machine. It is not clear how this affected the final results or if it had any effect at all.

EPA raises questions about (a) recalibration of the continuous gas analyzer (CGA) following service by the manufacturer prior to beginning Run 7 (see pa ge 47 of Final Study Report) and documentation of this recalibration

, (b) the potential impact of the ch ange in pressure drop across the CGA as a result of such service , and (c) potential effect of the CGA being connected to the reactor system exhaust during post

- run steam cleaning for part of Run 9 and all of Run 12

. Items (a) and (c) were addressed in t he July 1 2 , 2013 electronic mail message to Joe Avcin (EPA) from Phil ip Taylor (UDRI). The potential impact of the change in pressure drop across the CGA as a result of CGA service is addressed here.

The October 7, 2009 Corrective Action Form by Richard Striebich (included in Appendix 1 to the Final Study Report) concerning the CGA flow sensor bypass provides a starting point. This Corrective Action Form explains that the CGA read low for CO 2 followin g the flow sensor bypass, referring to the low readings for CO 2 during Runs 7, 8, and 9 as the result of drift. Review of the CO 2 readings in Table 14 of the Final Study Report and in the relevantPage 5 of 5 run checklists before and after the CGA flow sensor bypas s in Appendices 49 and 58 of the Final Study Report as well as pages 61

- 65, 67

- 68, 72, 78

- 82 Richard Striebich’s Phase II notebook in Appendix 36 of the Final Study Report indicates that the change in back pressure (pressure drop across the CGA) apparent ly contributed to this drift. As the stoichiometric calculations in Appendix 10 to the Final Study Report show, reactor pressure = room pressure + back pressure. Using 740 torr as a typical value for room pressure, the ratio of reactor pressure with 14 in ches W.C. back pressure to reactor pressure with 22 inches W.C. is 0.98. This ratio is within the span gas

- based correction factor used for CO 2 in Tab le 14 of the Final Study Report, indicating that the change in back pressure helps account for the CO 2 drift during runs 7, 8, and 9.

As t he October 7, 2009 Corrective Action Form notes, the full CGA recalibration for CO 2 prior to beginning run 10 brought the CGA readings for CO 2 back to the same levels ob served before CGA service and t h e correction factor using known and measured CO 2 concentration of span gas corrected the run average CO 2 values in Table 14 of the Final Study Report. Hence, the impact of the change in pressure drop across the CGA has been accounted for in the Final Stu dy Report.

3

. Area #6

– Other Perfluorinated Compounds The identity of the ions associated with some peaks in the chromatograms at various points during the experiment were not clear. What is the likelihood that there were other perfluorinated compounds present in the samples?

EPA asks whether unmarked apparent peaks in the LC/MS/MS chromatograms for experimental runs represent other perfluoroinated compounds in the samples.

Examination of the chromatograms by an LC/MS/MS expert indicates that the unmarked apparent peaks on these chromatograms were instrument noise . Furthermore, review of the LC/MS/MS analytical method (Exygen Method No.: 1M

- 008

- 046 Revision 1 as modified by the ECA) specified in the QAPP and included in the Fina l Study Report ( included in Appendix 69 to the Fluoropolymers Final Study Report) shows that the only transition monitored was 413  369, confirming that the only analyte determinable by the LC/MS/MS method in use was the PFO anion.