1. AXYS developed a method for direct injection analysis of 9 perfluoroalkyl carboxylates (PFCA), 3 perfluoroalkyl sulfonates (PFSA) and perfluorooctane sulfonamide (PFOSA) for use primarily in rapid and accurate characterization of sites affected by aqueous film-forming foams (AFFF). PFAS are anthropogenic chemicals of increasing concern due to their chain length- dependent persistence and bioaccumulation potential, adverse health effects, and widespread distribution [1]. AFFFs containing PFOS and other perfluorinated surfactants have been widely used for fire-fighting, resulting in contamination of ground and surface water around airports and other areas of high-volume use [2]. Aqueous samples containing fluorinated surfactants are complex matrices with high potential for analytical uncertainty arising from sub-sampling and high analyte concentrations [3]. Bharat Chandramouli, Million Woudneh, Coreen Hamilton, John Cosgrove – Axys Analytical Services, Sidney BC A Direct Injection LC-MS/MS Whole Water Method for the Analysis of Polyfluorinated Compounds from AFFF-affected Aqueous Samples ACKNOWLEDGEMENTS REFERENCES bharat@axys.com Figure 1: Analytes of Interest BACKGROUND RESULTS EXPERIMENTAL PROTOCOLS Table 2: Method Validation Data Method validation shows good accuracy and precision. Method quantitation range is suitable for site characterization. S TRATIFICATION AND C ONTAINER T ESTS Samples with high surfactant/PFC concentrations can demonstrate analyte stratification in the sample container [3]. Objectives Select appropriate sub-sample and estimate sampling variability by depth in container. Conduct tests to determine extent of stratification of analytes in various AFFF affected samples. Test Samples Three AFFF-affected groundwater samples were selected based on varying analyte concentrations and physical appearance. The samples were each in a full 1L HDPE bottle. Protocol Each sample was sub-sampled at three depths in triplicate: 1) 0.5 cm from the top surface or foam, 2) At the middle of the 1 L bottle, 3) 0.5 cm from the bottom of the container or 0.5 cm above any settled solids Figure 3: Matrix Effects – Precipitation Complex samples require smaller sample sizes. Range of sample sizes (50-750 µL) shown. Samples with precipitate show low recovery of labeled standards. Sample analyzed at smaller sample size of 50 µL. Showed acceptable surrogate standard recoveries. In most cases, lower sample sizes do not affect data quality. Figure 2: Effects of Solvent Composition Perfluoroalkyl carboxylates (PFCA) – 9 congeners Perfluroalkyl sulfonates (PFSA) – 3 congeners Perfluorooctane sulfonamide (PFOSA) – 1 congener O PTIMIZED M ETHOD P ROTOCOL Sub-sample (0.75 mL) from top of sample container, mix with 0.25 mL of methanol containing 0.3% ammonium hydroxide and an isotopically labelled standard mix. Perform LC-MS/MS using Waters 2690 liquid chromatograph coupled to Micromass Quattro Ultima triple quadrupole mass spectrometer operating in negative mode. Figure 4: Effect of Sampling Depth Figure 5: Comparison of Direct Injection with Reference SPE Method S OLVENT C OMPOSITION T ESTS Test reagent water and 4 basic methanol compositions: 50:50, 75:25, 85:15 and effective 100:0 at 3 different spiking levels ranging from 0.16 µg/L (low) to 400 µg/L (high). M ETHOD V ALIDATION Initial precision and recovery tests in reagent water using 1 blank + 4 replicates fortified at 33- 66 µg/L (higher for PFAS). Method detection limit tests based on 8 replicates of samples fortified at 0.16-0.33 µg/L (higher for PFAS). C OMPARISON WITH R EFERENCE M ETHOD Objective To compare a 0.75 mL subsampled direct injection method with the reference 50 mL whole sample vial, SPE method. Protocol 10 ground/surface water samples from sites affected by AFFF application were selected. For the reference method, 50 mL samples were fortified with an isotopically labelled standard mix and extracted using an Oasis WAX cartridge and analyzed by LC-MS/MS using the same instrumental protocol. For the direct injection method, a sample size of 0.75 mL (or lower) was used. Table 1: Composition of FC203CF – A typical sulfonate- containing AFFF formulation [4] Component Composition (%) Water69.0−71.0 Diethyleneglycolbutylether (butyl carbitol)20.0 Amphoteric fluoroalkylamide derivative1.0−5.0 Alkyl sulfate salts1.0−5.0 Perfluoroalkylsulfonate salts0.5−1.5 Triethanolamine0.5−1.5 Tolyltriazole (corrosion inhibitor)0.05 At lower % organic amounts, longer chain PFCs are retained (container effect). Especially pronounced at low concentration. Selecting 75% aqueous was optimal. Excellent precision observed at every depth of the 1 L bottle. Subsampling shows good reproducibility at every depth for all analytes except PFOS. PFOS shows modest stratification at top layer of bottle. Difference from mid layer is statistically significant (t test, p<0.05). For high-concentration samples, PFOS RPD is of the order of 20%, within inter-batch method variability. Direct injection method compares well with the reference method for all analytes. Method handles high analyte concentrations in AFFF-containing water samples. Subsampling does not have a significant effect on measurement uncertainty. A direct injection method has been developed for detection of PFC analytes in samples affected by AFFF application. Method applicable for samples containing >300 ng/L PFOS, 100 ng/L of PFOA and similar concentrations of other PFCs. Analysis shows good agreement with a reference whole sample SPE method over a broad range of concentrations. Solvent composition tests show that a minimum of 15% ammoniacal methanol is required to avoid low recoveries of C9-C12 perfluorinated carboxylic acids. 25% ammoniacal methanol in water provides optimal performance. Subsampling variability tests show excellent reproducibility at each sampling depth for all analytes and good reproducibility between sampling depths for all analytes except PFOS, which shows some evidence of stratification leading to 20-25% higher concentrations in the top layer. 1. Lindstrom, A. B., Strynar, M. J. & Libelo, E. L. Polyfluorinated Compounds: Past, Present, and Future. Env. Sci Technol 45(19), 7954–7961 (2011). 2. De Solla, S. R., De Silva, A. O. & Letcher, R. J. Highly elevated levels of perfluorooctane sulfonate and other perfluorinated acids found in biota and surface water downstream of an international airport, Hamilton, Ontario, Canada. Environ. Int. 39(1), 19–26 (2012). 3. Chandramouli, B., Cosgrove, J., Grace, R., Hoover, D. & Streets, S. Subsampling heterogeneity of high surfactant activity aqueous samples: Implications for perfluorinated compound analysis. SETAC (2010). 4. MSDS No. CKQCB. 3M Company; St. Paul, MN: Dec 17. 1999 FC-203CF Lightwater (TM) AFFF 3%. 5. AXYS Method MLA-060: Analysis of Perfluorinated carboxylates and sulfonates (2013). Differences are in the range of inter-batch variability as established by the initial precision and recovery analyses. Comparison with the reference whole-sample SPE method analysis shows equivalent results, indicating that subsampling variability is within experimental error. Certain samples require much smaller sample sizes due to precipitation during methanol addition. Sample processing time is reduced by >60% with no loss in method accuracy/precision compared with the reference method. Method is suitable for accurate characterization of sites affected by potential PFC contamination with high analyte concentrations and high surfactant activity. SUMMARY We thank the AXYS staff for their contributions to sample analysis.