CHARACTERIZATION OF TEAR GAS RESIDUES BY ION MOBILITY SPECTROMETRY

In this study a hand-held ion mobility spectrometer was used to charac terize the vapors produced by cu-chloroacetophenone (CN) and 2-chlorob enzylidenemalononitrile (CS), their isomers, and their degradation pro ducts at ambient temperature and 50 degrees C, and in both the positiv e-and negative-ion acquisition modes, Minimum determinable residues we re as follows: in the negative-ion acquisition mode at ambient tempera ture, CN 0.5 mu g, CS 10 mg; at 50 degrees C, CN 0.5 mu g, CS 16 mu g; and in the positive-ion acquisition mode at ambient temperature, CN 0 .5 mu g, CS not detected; at 50 degrees C, CN 0.1 mu g, CS not detecte d, The steady-state reproducibility was found to be independent of ion acquisition mode but dependent on signal intensity and background noi se [relative standard deviation (RSD) 3-17%]--the smaller the signal, the greater the variation, The day-to-day variation in positive-and ne gative-mode signal intensities showed the same trends (RSD 3-33%), By comparing positive-and negative-ion mode spectra, it was possible to d ifferentiate not only between CN and CS but also between their isomers and breakdown products.