Zeng Xia, Massey Simonich Staci L, Robrock Kristin R, Korytár Peter, Alvarez-Cohen Lisa, Barofsky Douglas F
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA.
Environ Toxicol Chem. 2008 Dec;27(12):2427-35. doi: 10.1897/07-570.1.
With the phaseout of the manufacture of some polybrominated diphenyl ether (PBDE) formulations, namely penta-brominated diphenyl ether (BDE) and octa-BDE, and the continued use of the deca-BDE formulation, it is important to be able to predict the photodegradation of the more highly brominated congeners. A model was developed and validated to predict the products and their relative concentrations from the photodegradation of PBDEs. The enthalpies of formation of the 209 PBDE congeners were calculated, and the relative reaction rate constants were obtained. The predicted reaction rate constants for PBDEs show linear correlation with previous experimental results. Because of their large volume use, their presence in the environment, and/or importance in the photodegradation of the deca-BDE formulation, BDE-209, BDE-184, BDE-100, and BDE-99 were chosen for further ultraviolet photodegradation experiments in isooctane. The photodegradation model successfully predicted the products of the photochemical reactions of PBDEs in experimental studies. A gas chromatography retention time model for PBDEs was developed using a multiple linear regression analysis and, together with the photodegradation model and additional PBDE standards, provided a way to identify unknown products from PBDE photodegradation experiments. Based on the results of the photodegradation experiments, as well as the model predictions, it appears that the photodegradation of PBDEs is a first-order reaction and, further, that the rate-determining step is the stepwise loss of bromine. Our results suggest that, based on photodegradation, over time, BDE-99 will remain the most abundant penta-BDE, while BDE-49 and BDE-66 will increase greatly and will be comparable in abundance to BDE-47.
随着某些多溴二苯醚（PBDE）配方产品的停产，即五溴二苯醚（BDE）和八溴二苯醚，以及十溴二苯醚配方产品的持续使用，能够预测更高溴化同系物的光降解情况变得很重要。开发并验证了一个模型，用于预测多溴二苯醚光降解的产物及其相对浓度。计算了209种多溴二苯醚同系物的生成焓，并获得了相对反应速率常数。多溴二苯醚预测的反应速率常数与先前的实验结果呈线性相关。由于BDE-209、BDE-184、BDE-100和BDE-99大量使用、存在于环境中以及在十溴二苯醚配方产品的光降解中具有重要性，因此选择它们在异辛烷中进行进一步的紫外光降解实验。光降解模型在实验研究中成功预测了多溴二苯醚光化学反应的产物。使用多元线性回归分析开发了多溴二苯醚的气相色谱保留时间模型，该模型与光降解模型及其他多溴二苯醚标准品一起，为鉴定多溴二苯醚光降解实验中的未知产物提供了一种方法。基于光降解实验结果以及模型预测，多溴二苯醚的光降解似乎是一级反应，而且进一步表明，速率决定步骤是溴的逐步损失。我们的结果表明，基于光降解，随着时间的推移，BDE-99仍将是最丰富的五溴二苯醚，而BDE-49和BDE-66的含量将大幅增加，其丰度将与BDE-47相当。
