Document BRN2XOG236kob76MzOjNBLBgo

AR226-3364 Biotransformation of 14C-Labeled Fluorotelomer Substances by Soil Microorganisms Wang N .1. Szostek B.2, Buck R.C.3, Folsom P.W. 1, Sulecki L.1, Powley C.2, Berti W .1, and Gannon J.T.1 1DuPont Central Research and Development, Newark, USA; 2 DuPont Haskell Laboratory; USA ; 3 DuPont Chemical Solutions Enterprise, USA. Introduction Growing public interest in the environmental fate o f fluorinated chemicals due to the global presence o f perfluorinated acids such as perfluorosulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). 8-2 TelomerB Alcohol (8-2 TBA, CF3(CF2)6CF2CH2CH2OH) is a major raw material used in the manufacture o f sales products (e.g. fluorosurfactants and fluoropolymers). The chain length, (CF2)g, is representative o f the telomer intermediates used to manufacture sales products. Materials and Methods Soil: Sassafras soil - pH = 5.5, OM = 2.9%, Sandy loam, Microbial Biomass = 154.4 pg carbon /g dry soil. Study Material: Custom synthesized 'X -labeled 8-2 TBA (CFJ(CF2)6:^CF2CH2CH2OH) a t~ 180 pg Kg-' soil. Additional Carbon source: ~ 50 mg ethanol (as cosolvent) Kg soil. ExperimentalSystem: Closed bottles (10 g soil plus substance solution in I27-mL bottles). The experimental duration is up to one year and the 0 2content and the respiration rate of the soil were monitored during the study. Extraction: l a: CH3CN (acetonitrile) at room T for several days; 2Bd: 90% CH3CN + 20 mM NaOH at 50 C overnight. The 1st and 2nd extract solutions were analyzed separately by LC/ARC. Analysis: LC/ARC (On-Line Chromatograph/Accurate Radioisotope Counting) and quadruple time of flight mass spectrometry (Q-TOF-MS) for 14C-metabolite quantification and identification, and LC/MS/MS for PFHA [C F^CF^CO O H ] quantification. u C-volatile trapping: 10 mL o f headspace gas were passed through Two C]8. cartridges (0.6 g each) mounted in tandem to trap organic volatiles and the cartridges were eluted with 5 mL o f CH3CN. UC 02 trapping: The headspace gas after passing through two C18. cartridges was trapped in 5 m L o f 1N of NaOH. f Physical Properties and Purity of the Test Substance - cf3(CF2)6!KFjCHjCHjOH "A DifficultrtoTest Substance" Low solubility 150 pgL'1 Vapor pressure 3 Pa at 21 C Adsorption to surfaces A Chromatogram of HPLC Characterization of Radiochemical Purity of the Test Substance Time (min) Figure 1 TABLE 1. LC/ARC peak number, acronym, structure, and molecular weight of the metabolites o f "C-iM TBA biodegradation LC/ARC Acronym Structure PcakDeflniUve structure determinations Number are In Progress Molecular Mass CF,(CFj)i|4COOH (PFOA) and an unknown CF,(CFJ)s,`CF=CFCHICOOH CF1(CFj)sMCH2CH2COOH Unknown 4 8-2 unsaturated acid 99995 2H.2H.3H, 3H-PFDA ^ 6 " CF!(CF2)si`CF2CH1CHjOH (Parent) CF1(CF2)tl`CF!CH2CHO and/or CFj(CFj)4'4CF=CHj? 7 8 CF,(CFj),COOH 99998-2 TBA ^ -- 8-2 FTAL and'or 8-2 FT Olefin PFHA Study Objectives To answer the following questions; Is 8-2 TBA readily transformable in soil? What are the potential metabolites o f 8-2 TBA biotransformation? What are the likely pathways for 8-2 TBA biotransformation? Are alternative biotransformation pathways available to metabolize 8-2 TBA beyond PFOA? Does microbial a-oxidation involve in 8-2 TBA transformation to form perfluorononanoic acid [CF3(CF2)6! :CF2CO O H ; PFNA]? Can 8-2 TBA and potential metabolites be strongly adsorbed to the soil and thereby not bioavailable? Results and Discussion - Figure 2 [3-:4]-8-2 TBA (peak 7) is transformed to other metabolites. - Over 90% o f J4C-8-2 TBA was converted at day 14, the majority o f the metabolites observed were not volatile. PFOA, an unknown metabolite (overlapping peak 3) and 2H,2H,3H,3H-PFDA (peak 5) are the major metabolites at day 84. 8-2 unsaturated acid (peak 4) was formed from day 1-2, but was converted after day 7. Peak 6 is major metabolite from day 1-7, but is not present after day 28. Two unknown :4C-metabolites (peaks 1&2), with molecular weight less than PFOA (retention time < PFOA), were observed during the study. - They may be possible intermediates for PFHA formation. Peak 8 was formed from day 1-7, but was not present after day 7. - Transient intermediate(s) accounting for small percentage o f the mass balance. * No CF3(CF2V *CF2COOH (PFNA) was detected. - Microbial a-oxidation of 14C-8-2 TBA was not observed. qjffPME The m iracles o f science' Results and Discussion - Figure 2 Results and Discussion Results and Discussion - Figure 3 \ Day 1 ; Day 14 6 j /i ! '} --- . 1 ----_ -.-ezre:-- -- j Day 2 \ 7 Day 28 5 i Day 7 / Li \ : Day 148 (sterile control) Day 84 3 CH.CN Exvsctebfe Material ,, Day 84 - 2Bdextraction j (+0.02 M NaOH) 'Sound' Materia! ? . Jr Figure 2 LC/ARC Chromatograms of ^O-parent and metabolites Results and Discussion - Figure 4 Minimal Alcohol Volatility The volatility o f :,C-8-2 TBA once applied to the soil was minimal. - Only - 2% of UC was detected in the headspace over 45 days. - No additional l<:0containing organic volatiles were detected after day 24. Strong adsorption to the soil and rapid conversion to other non-volatile metabolites significantly decrease the potential for alcohol release to air from soil. Figure 4 sequestration-' Observed 1<COa Release: Evidence of Fluorocarbon Chain "Degradation" uC-parent and metabolites are strongly adsorbed to the live soil, probably to the soil organic matters, within 7 days. - After day 7, about 50% o f the :,'C-parent and metabolites became unrecoverable by conventional solvent extraction methods (CH3CN, ethanol, acetone, THF, or MTBE at 50C; CH3CN plus 1 M NaCl, CH3CN plus 1 M HC1). - Only 0.5% triethylamine and 0.020-1 M NaOH plus CH3CN at 50 C overnight gave a good recovery for samples between days 7-28. - After day 28, even 20 mM NaOH plus CH3CN at 50 C overnight can only gave a partial recovery of the HC from the soil. 2% :iC 0 2 was detected in the headspace of the live soil sample bottles. Indicates that the fluorinated l3(Cj)-carbon has been de-fluorinated and mineralized. The loss of :4C-labelmg should result in metabolites with fluorocarbon chain lengths less than 8. Days after th e initiation Figure 3 - Cobalt-60-sterilized, but not autoclaved soil, resulted in near complete recovery (even at day 84) o f `"C-parent and fluorinated carboxylic acids spiked (dosed) into the soil at day 0. (CF3(CF2)s,4CF2CH2CH2OH, CFjiCF^CFjCHjCOOH, CF3(CF2)5CF= CFCH2COOH, PFOA, and PFHA) Results and Discussion - Figure 5 PrfiuGrobxanoitt A dd Formation - Fluorocarbon Chum "Degradation" Possible Biotransformation : _ Pathways in Soil ...... CF3(CF2V 'iCF2CH2CH2OH CF3(CF2)sI-,i T 2CHjCHO 1 C F jiC F^C P sC H jC O O H iCFjCFjV^F-CHj.. i^2H* + 2e- C Fj tC F jV '- O H -C H ji CFjct ^ TKHCOOH Termina! carbon oxidation and decarboxylation cycles PFHA formation is significant. At day 56, it accounted for about 14% o f tiie mass balance. The third and fourth perfiuorinated carbons have been defluorinated and mineralized. This shows that alternative metabolic pathways are available to metabolize 8-2 TBA beyond PFOA. jFigure 5 Peak 6 Conclusions [3-i,50 ] - 8-2 TBA was rapidly transformed. PFOA, an unknown metabolite and 2H,2H,3H,3H-PFDA are the prevalent metabolites at day 84. - A substantial amount are strongly sorbed and not easily extracted. No PFNA was observed. Minimal 8-2 TBA volatility was observed. Acid Metabolites identified are not expected to have potential for release to air and long-range atmospheric transport. Significant l4C 0 2 evolution and PFHA were observed. - Indicate that biotransformation pathways are available which metabolize multiple -CF2- groups resulting in metabolites with less than eight fluorinated carbons. The mimeies o f science*