Characteristics of azaarenes and dioxins in gases emitted from waste incinerators

In this study, we propose an analytical method to determine the fourteen of azaarenes present in flue gas samples collected according to Japanese Industrial Standard K 0311, which designates the method for the determination of dioxins in flue gas. Azaarenes can be analyzed using the acidic water phase after shaking extraction with dichloromethane, which is unnecessary for dioxin analysis. Flue gas samples were obtained from 24 waste incinerators in Japan, and azaarenes were detected in all the flue gas samples (0.21–3800 μg/m³ _N). The most abundant of the detected compounds were quinoline and isoquinoline. The concentration of azaarenes had a tendency to increase with that of polychlorinated dibenzo-p-dioxins and dibenzofurans. The isomer distribution of heptachloro-dibenzofurans (HpCDFs) was calculated using the computed Gibbs energy of formation (ΔG _f ) obtained by the semiempirical molecular orbital method at various temperatures. The calculated isomer distribution was fitted to the measured value of HpCDFs. It seems that the temperature obtained from the fitting calculations is an indicator of the cooling capacity of the combustion gas in an incinerator. The computed ΔG _f also explained the measured isomer distributions of azaarenes. It is suggested that the isomer distribution of azaarenes in the combustion process is thermodynamically controlled. This work was presented in part at the International Conference on Combustion, Incineration/Pyrolysis, and Emission Control, 2006, Kyoto     

Predictions for isomer distributions of toxic dioxins and furans in selected industrial combustion processes

Three thermodynamic databases of polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) have been used to simulate the PCDD/F isomer distribution in industrial combustion processes. The three databases had been derived using the Group Additivity approach and two computational molecular modelling methods, Modified Neglect of Diatomic Overlap (MNDO) and Parametrized Model 3 (PM3), respectively. The predictions of the toxic PCDD/F isomer distributions using the three different databases have been compared with measured values from industrial processes. An excellent agreement between the predictions using the MNDO method and the measured data has been obtained. It is concluded that the PCDD/F isomer distributions within each group observed in these combustion processes may be thermodynamically controlled.     

硝基芳烃为衍生物的定量结构-活性关系

对硝基芳烃类衍生物进行半经验分析轨道MNDO计算 ,求得全优化几何构型和电子结构。发现硝基氧原子的电荷平均值Q以及分子的LUMO能级值ELUMO与实验毒性呈线性相关 ,其多项式相关方程为 :-lgEC50 =9.1 0 7+1 9.54Q - 0 .996ELUMO,r=0 .949,F=1 0 .2 7(>F0 .0 0 1 )。无论从相关系数 ,还是从显著性检验看 ,-lgEC50 与Q和ELUMO之间存在非常显著的相关关系。并由此推测硝基芳数落向藻类细胞膜内的扩散过程及其随后与亲核基质相作用形成负离子自由基代谢产物的过程是其藻类致毒作用的控制步骤     

二正烷基亚硝胺第二活性区对致癌作用机理的理论研究

采用ＭＮＤＯ方法计算了对称二烷基亚硝胺β－,γ－和δ－位硫酸酯经ＳＮ２反应机制与ＤＮＡ碱基腺嘌呤（Ａ）发生烷化反应的速率控制步骤的势能曲线和活化能,以及β－位硫酸酯经邻基参与作用的腺嘌呤烷化反应过程的势能变化。结果表明,邻基参与作用有利于促进了烷基亚硝胺与ＤＮＡ的烷化反应,提高了β－位硫酸酯烷化ＤＮＡ的能力,以此可以解释β－位硫酸酯化的二烷基－Ｎ－亚硝基化合物的致癌活性大于γ－和δ－位硫酸酯化的二