Accelerated Articles Simultaneous Characterization of Perfluoroalkyl Carboxylate, Sulfonate, and Sulfonamide Isomers by Liquid Chromatography-Tandem Mass Spectrometry Jonathan P. Benskin, Mahmoud Bataineh, and Jonathan W. Martin* Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, 10-102 Clinical Sciences Building, University of Alberta, Edmonton AB, Canada T6G 2G3 A comprehensive method was developed to simulta- neously separate and detect perfluorinated acid (PFA) and PFA-precursor isomers using liquid chromatography- tandem mass spectrometry (LC-MS/MS). A linear per- fluorooctyl stationary phase and acidified mobile phase increased separation efficiency, relative to alkyl stationary phases, for the many perfluoroalkyl carboxylate (PFCA), perfluoroalkyl sulfonate (PFSA), and perfluorooctyl sul- fonamide (PFOSA) isomers and in combination with their distinct MS/MS transitions allowed full resolution of most isomers in standards. Utilizing the absence of the “9- series” and “0-series” product ions, several perfluorooc- tane sulfonate (C 8 F 17 SO 3 - , PFOS) isomers were struc- turally elucidated. In human serum, only perfluorooctane sulfonamide (C 8 F 17 SO 2 NH 2 , FOSA) and PFOS consisted of significant quantities of branched isomers, whereas PFCAs were predominantly linear. Interferences that coelute with the m/z 499 f 80 transition of PFOS on alkyl stationary phases were simultaneously separated and identified as taurodeoxycholate isomers, removal of which permitted the use of the more sensitive m/z 80 product ion and a resulting 20-fold decrease in PFOS detection limits compared to the m/z 499 f 99 transition (0.8 pg versus 20 pg using m/z 80 and 99, respectively). Interferences in human serum which caused a 10-20- fold over-reporting of perfluorohexane sulfonate (C 6 F 13 SO 3 - , PFHxS) concentrations on alkyl stationary phases were also simultaneously separated from linear PFHxS and identified as endogenous steroid sulfates. PFOSA iso- mers, generated with human microsomes, had different rates of metabolism, suggesting that the perfluoroalkyl branching pattern may affect the biological properties of individual isomers. This fact, and for reasons of improved accuracy and sensitivity, investigators are urged to utilize more efficient separation methods capable of isomer characterization in perfluoroalkyl research. Perfluorinated acids (PFAs) and their precursors (PFA-precur- sors) have received increasing scientific attention since 2000 when it was first recognized that PFAs were globally distributed in wildlife 1 and humans. 2 PFA-precursors, chemicals capable of being oxidized to PFAs, may contribute significantly to the environmen- tal and human burden of PFAs through atmospheric reactions, 3-5 biotransformation, 6-8 or perhaps some combination thereof. The concentrations of PFAs in human blood and remote wildlife (i.e., * Corresponding author. Phone: 780-492-1190. Fax: 780-492-7800. Email: Jon.Martin@ualberta.ca. (1) Giesy, J. P.; Kannan, K. Environ. Sci. Technol. 2001, 35, 1339-1342. (2) Kannan, K.; Corsolini, S.; Falandysz, J.; Fillmann, G.; Kumar, K. S.; Loganathan, B. G.; Mohd, M. A.; Olivero, J.; Van Wouwe, N.; Yang, J. H.; Aldoust, K. M. Environ. Sci. Technol. 2004, 38, 4489-4495. (3) Martin, J. W.; Ellis, D. A.; Mabury, S. A.; Hurley, M. D.; Wallington, T. J. Environ. Sci. Technol. 2006, 40, 864-872. (4) Ellis, D. A.; Martin, J. W.; De Silva, A. O.; Mabury, S. A.; Hurley, M. D.; Sulbaek Andersen, M. P.; Wallington, T. J. Environ. Sci. Technol. 2004, 38, 3316-3321. (5) D’eon, J.; Hurley, M.; Wallington, T. J.; Mabury, S. A. Environ. Sci. Technol. 2006, 40, 1862-1868. (6) Martin, J. W.; Mabury, S. A.; O’Brien, P. J. Chem. Biol. Interact. 2005, 155, 165-180. (7) Tomy, G. T.; Tittlemier, S. A.; Palace, V. P.; Budakowski, W. R.; Braekevelt, E.; Brinkworth, L.; Friesen, K. Environ. Sci. Technol. 2004, 38, 758-762. (8) Xu, L.; Krenitsky, D. M.; Seacat, A. M.; Butenhoff, J. L.; Anders, M. W. Chem. Res. Toxicol. 2004, 17, 767-775. Anal. Chem. 2007, 79, 6455-6464 10.1021/ac070802d CCC: $37.00 © 2007 American Chemical Society Analytical Chemistry, Vol. 79, No. 17, September 1, 2007 6455 Published on Web 08/01/2007