MeOH, EtOH, i-PrOH or Me2CHCMe2OH - contg. dry air samples (50 ppb to 150 ppm, 50 ppb-2.5 ppm, 80-300 ppb and 50-80 ppb, resp.) were ionized in differential ion mobility spectrometer. The spectra were recorded and analyzed to detect the ion decompn. This was obsd. for all compds. tested except for MeOH. The effective temp. was detd. to be 254, 277 and 103 degrees C for EtOH, i-PrOH and Me2CHCMe2OH, resp.