Purity not reported in methods or the results but was verified.

"The CPFB (C6ClF5) used in this study was purchased from Aldrich Chemical Co. (Milwaukee, WI). The purity of the test material was determined by capillary gas chromatography. A Varian 3700 gas chromatograph (Varian Associates, Palo Alto, CA) equipped with an electron capture detector was used in conjunction with a Hewlett-Packard 3388 computing integrator (Hewlett-Packard Co., Palo Alto, CA) to measure peak area and record chromatograms. CPFB was diluted in hexane to provide peak areas within the detection limits of the instrument. "