Pathway of diethyl phthalate photolysis in sea-water determined by gas chromatography-mass spectrometry and compound-specific isotope analysis.
Pathway of diethyl phthalate photolysis in sea-water determined by gas chromatography-mass spectrometry and compound-specific isotope analysis.
复制标题
DOI：
10.1016/j.chemosphere.2012.06.045
复制
发表时间：
2013
期刊：
影响因子：
8.8
通讯作者：
Xuewei Peng;Lijuan Feng;Xianguo Li
中科院分区：
文献类型：
--
作者：
Xuewei Peng;Lijuan Feng;Xianguo Li
采用中间产物检测和稳定碳同位素分馏相结合的方法，研究了天然海水中邻苯二甲酸二乙酯（DEP）在紫外光照射下的降解机理。用气相色谱-质谱（GC-MS）鉴定的典型中间体是邻苯二甲酸单乙酯（MEP）和邻苯二甲酸酐。稳定的碳同位素签名，通过燃烧接口（GC-C-IRMS）的同位素比质谱联用气相色谱法测定。残余DEP分子中δ 13 C同位素位移为12.3±0.3‰（f=0.09），明显的13 C富集是其光解的指示。反应位置同位素富集因子（εreactive position）和表观动力学同位素效应（AKIE）分别为−35.25±2.26‰和1.075，表明DEP光解的初始反应步骤是CO键的断裂。基于这些观察结果，提出了降解途径。首先，DEP分子中的一个CO键断裂形成MEP。然后，MEP进一步降解为邻苯二甲酸酐。我们的工作表明，特定化合物的同位素分析（CSIA），结合中间体分析，是一个可靠的手段来推断DEP的光解机制。该方法可作为复杂环境系统机理研究的参考。
The degradation mechanism of diethyl phthalate (DEP) in natural seawater under UV irradiation was investigated using a combination of intermediates detection and determination of stable carbon isotopic fractionation. Typical intermediates identified with gas chromatography–mass spectrometry (GC–MS) were mono-ethyl phthalate (MEP) and phthalic anhydride. Stable carbon isotope signature was determined by gas chromatography coupled with isotope ratio mass spectrometry through a combustion interface (GC–C–IRMS). A profound13C enrichment, with a δ13C isotope shift of 12.3±0.3‰ (f=0.09) in residual DEP molecule, was clearly an indicator to its photolysis. The reactive position isotope enrichment factor (εreactive position) and apparent kinetic isotope effects (AKIE) were −35.25±2.26‰ and 1.075, respectively, indicating that the initial reaction step was cleavage of a CO bond in DEP photolysis. Based on these observations, a degradation pathway was proposed. First, a CO bond in DEP molecule was broken to form MEP. Then, MEP was further degraded to phthalic anhydride. Our work demonstrates that compound-specific isotope analysis (CSIA), when combined with intermediates analysis, is a reliable measure to deduce the mechanism of DEP photolysis. This approach might be extended as a reference for mechanism investigation in complicated environment systems.