SENSITIVE IN-SITU DETECTION OF CHLORINATED HYDROCARBONS IN GAS-MIXTURES

We detect chlorinated hydrocarbons (CHC's) in gas mixtures by dissocia ting the CHC's with a 193-nm laser and measuring the subsequent concen tration of the CCl fragmentation by means of laser-induced fluorescenc e. Sub-ppm detection, where ppm indicates parts in 10(6), is achieved for C2H5Cl with a 10-mm3 measurement volume and integration over 50 la ser shots. Every other CHC tested is also detectable, with the same or better detection limits. The CCl forms promptly during the fragmentat ion laser pulse through unimolecular dissociation of the parent CHC's. The technique should be a useful diagnostic for CHC incineration syst ems.