Abstract
Both perfluoroisobutylene (PFIB) and hexafluoropropene (HFP) react in methanol with a mixture of pyridine and piperidine to produce a stable yellow color at 25° to 40°C which is measured spectrophotometrically at 412 mμ or visually compared with permanent secondary standards. In the presence of acetic acid only HFP undergoes the color-forming reaction with piperidine. The PFIB concentration can be determined by difference. The effect of various halogenated compounds with and without the R-C = CF2 (R = -F, -CF3) function is presented. With a 0.1-cubic-foot sample at 25°C, the method will detect 0.1 ppm of PFIB or 0.02 ppm of HFP. A lightweight easily portable field kit with a “Uni-Jet” aspirator has been developed for field surveys.