FORMATION OF CHLORINATED POLYCYCLIC AROMATIC-HYDROCARBONS IN DIFFERENT CHLORINATION REACTIONS

Eleven of the most commonly found PAHs were subjected to different chlorination reactions, the products formed being then analyzed by GC/MS. These reactions were performed in carbon tetrachloride solution and on carbon black or urban dust particles, and the influence of UV-irradiation on the formation of chlorinated products was studied. When dissolved in carbon tetrachloride and irradiated with UV-light, several chloro-added PAHs were formed, of which some have shown direct mutagenic effects in the Ames assay. A large number of isomers of chloro-substituted PAHs, mainly mono- and dichloro-derivatives, was also detected. Some of these were shown to be degradation products of the chloro-added compounds. UV-irradiation had a minor effect on the formation of chlorinated products, when the PAHs were adsorbed and chlorinated on carbon black or on urban dust particles. The chlorinated products were similar to those isomers formed when the solution of PAHs was chlorinated in the absence of light, i.e. mainly products originating from electrophilic aromatic substitution. The stabilities of chloro-PAHs towards photochemical degradation were shown to increase when adsorbed on soot particles. An increasing number of chlorosubstituents on the aromatic nuclei also enhanced the stabilities of the PAHs examined.