Document QgEyYJO4m8B4XzqX9EpaqND3o

BACK TO MAIN STABILITY IN THE ATMOSPHERE (PHOTOLYSIS) TEST SUBSTANCE Identity: Perfluorooctanesulfonyl fluoride. May also be referred to as: POSF or FX-8. (1-Octanesulfonyl fluoride, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8heptadecafluoro-) CAS: #307-35-7. Purity: 98%. Remarks: The Aldrich chemical lot number is 12517LR; test substance is a clear liquid at 25 C. METHOD References: T.J. Wallington et al, J. Chem. Phys. A 101, pp. 8264-8274 (1997), and references therein; W.B. DeMore et al, NASA Jet Propulsion Laboratory, JPL Publication No. 94-26 (1994); M.J. Molina et al, "Atmospheric Lifetime Studies of Some Halogenated Ethers (L-14055, L-14056, and L-14093)," report to the 3M Specialty Chemicals Division (March 1996); R.G. Prinn et al, Science 269, pp. 187-192 (1995). 3M developed the equipment and analytical techniques required to perform the study. GLP (Y/N): No, but many GLP procedures followed. Year completed: 2001 Type: Indirect Gas Phase Photolysis Test sample preparation: Gaseous reagents POSF, CH3Cl (at ppm levels), O3 , and H2O (at percent levels) were added to an evacuated reaction chamber/infrared absorption cell, with balance O2/He (40%/60%), to one atmosphere. O3was generated by illuminating the 40%/60% O2/He gas mixture with a short-wavelength UV source in a separate reaction chamber and transferring the resulting gas, which contained approximately 1% O3, to the reaction chamber. Samples were independently prepared immediately before the performance of two sample runs and five control runs. Analytical Procedures: FTIR techniques were employed to determine the sample concentrations of POSF, CH3Cl, and O3 about once per minute; the wavenumber regions employed were 1101.6 - 1320.7, 2824.5 - 3012.7, and 2052.5 - 2141.7 cm-1. Data were collected for approximately 120 minutes per analytical run. For the last ~60 minutes of each run, the mixture was illuminated with 300 to 600 Watts of UV radiation from a broad-band discharge lamp through a window of polished, semi-conductor-grade quartz. The filtered UV radiation generated the gas-phase hydroxyl radical (OH*) - but no additional O3 - in the reaction chamber. Least-squares analyses of the concentration data yielded six first-order rate constants describing the degradation of POSF, CH3Cl, and O3 due to interactions with both OH* and the chamber walls. 1 BACK TO MAIN RESULTS Degradation and breakdown products: Indirect photolysis of POSF was not observed in six of the seven sample and control runs. In one control run, with elevated CH3CI concentration, some degradation of POSF was observed in the presence of UV radiation and OH*. Comparison of the POSF degradation rate to the published rate constant of the reference CH3Cl, for this single run, leads to a POSF indirect photolysis half-life of 3.7 years under typical tropospheric conditions. CONCLUSIONS The study data generally indicate that reactions between POSF and the OH radical do not occur in the Earth's atmosphere. However, in one run out of seven, a run in which the reference compound monochloromethane (CH3Cl) was evaluated, we observed a slight decrease in the POSF concentration. The relative rates of degradation of POSF and CH3Cl observed in this single run are consistent with a POSF half-life of 3.7 years in the presence of typical tropospheric concentrations of the OH radical. Given the lack of degradation in the other six runs, however, it is likely that the actual atmospheric POSF half-life is potentially much longer, than 3.7 years. SUBMITTEE__________________________________________________________ 3M Environmental Laboratory, Building 2-3E-09, 935 Bush Avenue, St. Paul, MN 55106 DATA QUALITY Reliability: Klimisch ranking: 2 Remarks: Study was well conducted, though not under GLP. REFERENCES This study was conducted at the 3M Environmental Laboratory under Lab Request Number E01-0739. See 3M Laboratory Report No. E01-0739 (dated 12 June 2001) OTHER Last Changed: June 22, 2001 2