CHLORINATED DIPHENOQUINONES - A NEW CLASS OF DIOXIN ISOMERIC COMPOUNDS DISCOVERED IN FLY ASHES, SLAGS, AND PYROLYSIS OIL SAMPLES BY USING HPLC ELCD AND HRGC/MS/

Chlorinated 4,4'-diphenoquinones, previously unknown byproducts of the rmal processes in the presence of chlorine, have been discovered in a variety of samples such as oil products from a waste pyrolysis plant, a ny ash from a municipal waste incinerator, and a sample of Kieselrot slag. The pyrolysis plant products also contained tetramethylated and unsubstituted 4,4'-diphenoquinone, All compounds may be generated by oxidative coupling of phenols at elevated temperatures-a reaction that is considered to compete with the formation of the structurally isome ric dioxins. Once built-up, 4,4'-diphenoquinones form a redox pair wit h the corresponding 4,4'-dihydroxybiphenyls, with variable equilibrium positions depending on the prevailing conditions. For analysis, a cle anup method which involves liquid/liquid partition and solid-phase ext raction was developed. The method is suitable for the determination of all substances of this class. Quantitative analysis was carried out b y HPLC using an electrochemical detector for the fly ash and slag samp les. Pyrolysis oil samples were quantitatively analyzed by GC/MS after derivatization with trifluoroacetic acid anhydride, Substance identif ication in all samples was performed by GC/MS, The samples were found to be contaminated with chlorinated diphenoquinones in the lower and m iddle ppb range. Pyrolysis oil products yielded up to 1 ppm methylated diphenoquinones. The amount of diphenoquinones in the samples is comp ared with their yield of chlorinated dioxins and furans as well as pol ychlorinated biphenyls (PCBs). Kieselrot especially was contaminated, with 25 ppm of polychlorinated dibenzo-p-dioxins/-furans (PCDD/F) and 94 ppm of hexachlorobenzene, while the pyrolysis oil samples contained up to 360 ppb of PCDD/F and up to 25 ppm of PCB.