OCR Text |
Show about 0.5 -..... 1.0 seconds in the stage-two incineration process. Samples of C6H6' C6HsCH3 ' C6HsC2H3 and C6HsC2Hs \'lere taken with a pyrex tube at intervals of 30 sec and analyzed by use of the GC/FID. The glassfiber filter 'W'as used for sampling the particles and PAHs 'W'hich were in the solid phase. PUF (polyourethane foam) was used for sampling the PAHs 'W'hich were in the gas phase. The samples 'W'ere pretreated in the series process: extraction, concentration and purification , then the GC/MSD 'W'as used to analyze the 14 species of PAHs as sho'W'n in Table 1.. During extraction process, samples were extracted in a soxhlet extractor \\-'ith 250 ml of dichlormethane at 45°C for about 16 hr. After extraction, the dichloromethane extract \\:as dried to 1 ml - 2 ml by use of a rotory evaportor. The residue of extract was purified with 100 ml hexane-dichloromethane (7:3, v/v) in the tube purifier (¢ =100nm, L=20cm) \\-'hich was packed with 2 grams of activated alumium and 3 grams of silica gel. Finally, the purificatory samples were once concentrated to 2 ml by use of a rotary evaportor, and dried to 1 ml by use of the nitrogen. The mutagenic activity of the particulates and PUF extracts were tested by the Ames Salmonella/microsomal assay system [10,11] . From the previous studies, it was noted that the mutagenic response of strain T A 98 ,which was used to detect frame-shift substitution mutation, was significiantly higher than that of strain T A 100 ,which was used to detect base-pair substitution mutation, upon incubation with the dichloromethane extract of airborne particulates. Thus, Salmonella typhimurim strain T A 98 was employed to carry out the mutagenicity test in this study . . An aliquot of sample extracts in DMSO was delivered to a test tube containing 2 ml of molten top agar supplemented with 0.1 ml test solution, 0.1 ml of an overnight broth culture of the tester strain, with or without 0.5 ml S9 mixture. The S9 homogenate was prepared from the liver of Sprague-Dawley male rats pretreated for 5 days with Aroclor 1254 (500 mg/kg body weight) according to Maron and Ames et al. [11]. After a 2 days incubation of the culture plates at 37 C,histidine revertants of T A98 were scored . A positive mutagenic response was defined as a dose -dependent response giving at least a 2-fold increase in revertant colonies per plate as compared with spontaneous reversion . 5 |