2,2-双(对氯苯基)-1-氯乙烯稳定氯同位素组成测定的氧化脱氯前处理方法

2，2-双（对氯苯基）-1-氯乙烯又称p，p'-DDE，是农药p，p'-DDT重要的一级降解产物，在环境中广泛存在，对哺乳动物具有显著的雄性激素受体干扰效应。p，p'-DDE的稳定氯同位素δ37Cl值的测定可用于环境中化合物的示踪及迁移转化研究。本文报道了采用离子色谱法测定Cl-产率和GasBench-IRMS离线法测定p，p'-DDE δ37Cl值的氧化脱氯反应条件的优化，确定了最佳氧化脱氯反应条件。以CuO为氧化剂，通过氧化脱氯反应将p，p'-DDE中的有机态氯转换为Cl-，比较了真空度、不同反应温度和不同反应时间对Cl-产率和δ37Clproduct SOMC/‰值的影响。结果表明:在真空环境下，当p，p'-DDE与足量CuO反应时，δ37Clproduct SOMC/‰值与Cl-产率在500~720℃范围内满足线性方程y=1.44x-4.41，R2为0.96。且在720℃、反应1 h的条件下，p，p'-DDE δ37Cl值的测定误差最小，在±0.15‰以内。

Study on the oxidation dechlorination reaction for determination of chlorine isotopic composition of 1,1-dichloro-2,2-bis(4-chorophenyl) ethylene

1,1-dichloro-2,2-bis(4-chorophenyl)ethylene (p,p’-DDE) is the primary metabolite of 1,1'-(2,2,2-trichloroethane-1,1-diyl)bis(4-chlorobenzene) which is a pesticide.p,p’-DDE was ubiquitous in the environment, and has significant interference effect on the male hormone receptor in the mammal. The chlorine isotopic composition (δ37Cl) ofp,p’-DDE can be used to study the fate of the compound in environment. In order to obtain the optimal reaction conditions, the CuO catalysed oxidative dechlorination reaction ofp,p’-DDE were conducted under vacuum, different temperatures (520-900℃) and time (0.5-1.0 h). Cl– formed in the reaction was determined by ion chromatography and theδ37Cl was determined by GasBench-IRMS. The experimental results showed there is a linear dependence betweenδ37Clproduct SOMC/‰ and yield of Cl– whenp,p’-DDE reacted with enough CuO at 520℃ to 720℃ under vacuum condition. The linear equation wasy=1.44x–4.41 with 0.96 forR2. Besides, the error value ofδ37Clproduct SOMC/‰ forp,p’-DDE was lower than ±0.15 ‰ when the reaction conditions were 720℃ and 1h. In conclusion, a more effective and accurate preparative method was developed for the determination ofδ37Clproduct SOMC/‰ of semi-volatility organo-chlorine compounds.