Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
Chemosphere. 2013 Sep;92(11):1557-62. doi: 10.1016/j.chemosphere.2013.04.029. Epub 2013 May 18.
The photolysis of three phthalic acid esters (PAEs) (dimethyl (DMP), di-n-butyl (DBP), and di-n-octyl (DOP) phthalates) under ultraviolet (UV) irradiation at 254nm in laboratory experiments was investigated by gas chromatography coupled with isotope ratio mass spectrometry through a combustion interface (GC-C-IRMS). The degradation processes of DMP, DBP and DOP were well described by a first-order kinetic, with rate constants of 0.02636, 0.1005 and 0.958h(-1) for DMP, DBP and DOP, respectively, indicating that the photolysis rate of PAEs is related to the number of carbon atoms in molecule. The results of TOC analysis indicated that PAEs could not be completely mineralized under UV irradiation. Stable carbon isotope fractionation of the three PAEs produced during photolysis was evaluated with compound-specific isotope analysis (CSIA). Pronounced (13)C-enrichment, with maximum δ(13)C shifts of Δδ(13)CDMP=10.04±0.13‰ (f=0.09), Δδ(13)CDBP=7.4±0.19‰ (f=0.06) and Δδ(13)CDOP=2.9±0.17‰ (f=0.25) in the residual DMP, DBP and DOP, respectively, were clearly a direct evidence for photolysis of three PAEs. The order of stable carbon isotope fractionation of the three PAEs during photolysis, DMP>DBP>DOP, is an inverse function of the number of carbon atoms in molecule. The kinetic isotope effects (KIE) values, from 1.0018 to 1.0045 for the three PAEs, were consistent with the KIE values (1.00-1.03) of the C-O bond cleavage reported in literature.
实验室实验采用气相色谱-同位素比质谱联用仪（GC-C-IRMS），通过燃烧接口，在 254nm 紫外光照射下研究了三种邻苯二甲酸酯（PAEs）（邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二丁酯（DBP）和邻苯二甲酸二辛酯（DOP））的光解过程。DMP、DBP 和 DOP 的降解过程均很好地符合一级动力学，DMP、DBP 和 DOP 的速率常数分别为 0.02636、0.1005 和 0.958h(-1)，表明 PAEs 的光解速率与分子中碳原子的数量有关。TOC 分析结果表明，PAEs 在紫外光照射下不能完全矿化。采用化合物特异性同位素分析（CSIA）评估了光解过程中产生的三种 PAEs 的稳定碳同位素分馏。残留 DMP、DBP 和 DOP 中明显的（13）C 富集，最大 δ（13）CDMP 位移为Δδ（13）CDMP=10.04±0.13‰（f=0.09）、Δδ（13）CDBP=7.4±0.19‰（f=0.06）和Δδ（13）CDOP=2.9±0.17‰（f=0.25），这是三种 PAEs 光解的直接证据。三种 PAEs 光解过程中稳定碳同位素分馏的顺序，DMP>DBP>DOP，与分子中碳原子数量呈反函数关系。三种 PAEs 的动力学同位素效应（KIE）值在 1.0018 到 1.0045 之间，与文献中报道的 C-O 键断裂的 KIE 值（1.00-1.03）一致。
