Analytical Challenges and Environmental Analytical Challenges and Environmental Relevance of Branched and Linear Isomers of Relevance of Branched and Linear Isomers of Perfluorooctane Sulfonate and Related Perfluorooctane Sulfonate and Related Fluorinated Compounds in Biota Fluorinated Compounds in Biota Robert J. Letcher Robert J. Letcher 1,2 1,2 , Shaogang Chu , Shaogang Chu 1 1 , , Wouter A. Gebbink Wouter A. Gebbink 2 2 , Jason O , Jason O ’ ’ Brien Brien 3 3 and Sean Kennedy and Sean Kennedy 1 1 QUASIMEME Workshop, “Analysis of Perfluorinated Compounds”, Amsterdam, The Netherlands, Oct. 14-15, 2009 1 Wildlife Toxicology Section, Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada 2 Department of Chemistry, Carleton University, Ottawa, Ontario, Canada 3 Department of Biology, University of Ottawa, Ottawa, Ontario, Canada (contact e (contact e - - mail: mail: [email protected][email protected]) )
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Analytical Challenges and Environmental Analytical Challenges and Environmental Relevance of Branched and Linear Isomers of Relevance of Branched and Linear Isomers of
Perfluorooctane Sulfonate and Related Perfluorooctane Sulfonate and Related Fluorinated Compounds in BiotaFluorinated Compounds in Biota
Robert J. LetcherRobert J. Letcher1,21,2, Shaogang Chu, Shaogang Chu11, , Wouter A. GebbinkWouter A. Gebbink22, Jason O, Jason O’’BrienBrien33
and Sean Kennedyand Sean Kennedy11
QUASIMEME Workshop, “Analysis of Perfluorinated Compounds”, Amsterdam, The Netherlands, Oct. 14-15, 2009
1 Wildlife Toxicology Section, Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada
2 Department of Chemistry, Carleton University, Ottawa, Ontario, Canada3 Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
PFSA and precursor production:- 3M Company from the 1950s to 2001- 3M voluntary phase-out of its PFOSF-based chemicals in favour of shorter chain-length compounds- PFOS has been directly produced in China since 2003 - influence on global emission patterns
PFOS: Precursor Transformation/Degradation
Degradation of Perfluorosulfonamides to PFOSAbiotic degradation as well as in vivo & in vitro biotransformation in dogs, rats & rainbow trout
(Arrendale et al., 1989; Grossman et al., 1992, Tomy et al., 2004, Xu et al., 2004)
No furtherdegradation
N-Et-FOSA (N-ethyl-perfluorooctane sulfoamide)
F3C SO
NH
F F
F F
F F F F
F F F F
F F O
CH2CH3
F3C SO
O-
F F
F F
F F F F
F F F F
F F O
L-PFOS?
PFOSA (perfluorooctane sulfonamide)
F3C SO
NH2
F F
F F
F F F F
F F F F
F F O
What about isomer-specific transformation (metabolism) and degradation?
PFOS and Precursors Are Not a Singles Compound But Composed of Various Isomers
production of PFOS derivatives from linear alkyl precursors using ECF is not a clean process
commercial PFOS claimed to be generally >98% pure, but based on purity assessments using e.g., acid/base titration method after ion exchange with a strong acid resin
commercial PFOS contained approximately 86% PFOS; 70% L-PFOS and ~30% branched isomers (by 19F NMR):
(G. Arsenault, B. Chittim, A. Mclees, R. McCrindle, N. Riddell, B. Yeo. 2008. Chemosphere 70:616-625)
F3C SO
O-
F F
F F
F F F F
F F F F
F F OL-PFOS
P1MHpS P2MHpS P3MHpS
P4MHpS P5MHpS P6MHpS
F3CSO
F F
F F
F F F F
F F F
O
F3CSO
F F
F F
F F F
FF F FO
F3CSO
F F
F F
F F F
FF
F
FCF3
OCF3
F3C
F3CSO
F F
F F
F FF
FF F F
O
F3C
F3CSO
F F
F F
F F F
FF
F
FCF3
O
F3CSO
F F
F F
F FF
FF F F
O
F3C
O-O- O-
O-O-O-
P35DMHxSP44DMHxS P45DMHxS P55DMHxS
F3C SO
F
F F
F FF
F F
O
F3C
F3C
F3C SO
F F FF FF
F F
O
CF3
CF3
F3C SO
F
F
FF FF
F F
O
CF3
F3C
F3C SOFF
FF FF
F F
O
F3C
F3C
O- O- O- O-
(M. Houde, G. Czub, J.M. Small, S. Backus, X. Wang, M. Alaee, D.C.G. Muir. 2008. Environ. Sci. Technol.)
Limited Analytical and Environmental Study on Isomer-Specific PFOS; None For Other PFSAs
Up to this study, little known about environmental presence and fate of PFOS isomers
total of 6 isomers, 3 M-PFOS and 3 DM-PFOS isomers as well as linear L-PFOS detected in technical mixture, water, sediment and biota
L-PFOS >88% of total PFOS in all compared to technical PFOS (77%)
T-PFOS; 76% L-PFOS, 20% M-PFOSs and 3.6% DM-PFOSs
High L-PFOS suggested a reduced uptake of branched isomers, more rapid elimination of the branched isomers and/or a selective retention of the L-PFOS
Trophic magnification factor of L-PFOS (4.6) was greater than M-PFOS isomers (1.3), whereas DM-PFOS isomers showed no biomagnification
- homogenized sample in polypropylene centrifuge tube- IS spike: sodium perfluoro-1-[1,2,3,4-13C4]octane sulfonate (MPFOS); 100 ng/mL
Vortex Mixing and Filtration
- KOH (10 mM) acetonitrile/water (80/20 v/v) extraction- centrifuge, add water and vortex- pH = ~4 with 2% aq. formic acid- Oasis SPE-WAX (weak anion exchange) clean-up; pre-conditioned
Egg, Liver or Plasma sample
GC-MS(ECNI)
SIM m/z 137, 480, 499, 503
- 0.5 g tetrabutyl ammonimum hydroxide (TBAH) in 5 mL diethyl ether- sonication for 0.5 h, centrifugation, upper phase isolation- 100 uL of TBAH mixture added to sample fraction- addition 1 mL of ether added, centriguged and frozen at -20C- unfrozen ether phase transferred, to dryness and reconstituted in 100 uL ether
- sample loaded on SPE- SPE washed with 2% aq. formic acid (1 mL), 2×1 mL H2O, 2×1 mL MeOH- PFOS isomer elution with 2×1 mL NH4OH (28-30%) in aq. MeOH (1/9 v/v)
K+PFOS- from 3 suppliers by LC-ESI(-)-MS/MS: L-PFOS consistently 67-79%(G. Arsenault, B. Chittim, A. Mclees, R. McCrindle, N. Riddell, B. Yeo. 2008. Chemosphere 70:616-625)
Isomer-Specific PFOS Determination: LODs, MDLs and Recovery Efficiency
PFOS Isomer-Specific Toxicokinetics and Effects on Gene Expression in Chicken Eggs Injected With Technical PFOS
Liver PFOS Concentration of Exposed Embryos Increases With Dose
0.01
0.1
1
10
100
untreated DMSO 0.1 5 100Dose Group (ug/g)
Tota
l PFO
S (u
g/g
ww
)
(J.M. O'Brien, A.C. Carew, S.G. Chu, R.J. Letcher, S.W. Kennedy. 2009. Comp. Biochem. Physiol. Part C. 149:524-530)
Significant increase (p<0.05)±SE (2×3 sets of replicates)
Conclusions
New in-port GC-MS based method allows for complete quantitative assessments of all geometrical isomers known to be present in T-PFOS mixtures
Isomer-specific processes that favour L-PFOS occur in abiotic and more so in biotic compartments (e.g., wildlife and fish); selective uptake, bioconcentration, degradation, metabolism and/or bioaccumulation
As typified by Great Lakes herring gulls and circumpolar polar bears; highly conserved PFOS isomer pattern and enriched L-PFOS suggest isomer-specific processes occurring lower on the food web
PFOSA metabolism appears to occur in gulls and bears as a source of bioaccumulative PFOS: Isomer-specific?
Isomer-specific PFOS, as well as other precursors and PFCs (e.g., PFCAs and PFPAs), are currently not or under studied
Acknowledgements and Funding
Natural Sciences and Engineering Research Council (to R.J.L.)
Environment Canada’s Chemicals Management Plan (CMP)
Northern Contaminants Program (to R.J.L.)
Canadian International Polar Year (to R.J.L.)
Molson Foundation (to R.J.L.)
Danish Department of the Arctic Environment; Norwegian Polar Institute