| Co-Investigator(Kenkyū-buntansha) |
OIDA Tatsuo Dep. Chem. Mat. Tech., Kyoto Inst. Tech., Assoc. Prof., 工芸学部, 助教授 (90152032)
OTSUKA Koji Dep. Material Science, Himeji Inst. Tech., Assoc. Prof., 理学部, 助教授 (70183762)
TERABE Shigeru Dep. Material Science, Himeji Inst. Tech., Professor, 理学部, 教授 (50115888)
IKEGAMI Tohru Dep. Polymer Science, Kyoto Inst. Tech., Instructor, 繊維学部, 助手 (20301252)
HOSOYA Ken Dep. Polymer Science, Kyoto Inst. Tech., Assoc. Prof., 繊維学部, 助教授 (00209248)
|
|---|
| Research Abstract |
(1)PCBs and polychlorodibenzo-p-dioxins (PCDDs) were decomposed in a quartz column packed with octadecylsilylated silica particles (ODS-silica) by external UV irradiation. Continuous photolysis of highly chlorinated PCBs trapped on ODS-silica from aqueous solution was also possible. The photolysis of PCBs having two to eight chlorines allowed the examination of the factors that affect the reaction pathway. Steric congestion and molecular symmetry were found to be the major factors, explaining the seemingly complicated decomposition pathways of various congeners that were not much affected by the light source, a mercury lamp or sunlight. The results indicate that the predominant ortho-dechiorination leads to products having not only higher TEFs but also much longer life under photolysis conditions. PCDDs lose a chlorine atom preferentially from 2378-positions in the presence of H-donor, but preferentially from 1469-positions in the absence increasing TEQs, suggesting potential danger of
… More
sunlight photolysis of contaminated soil in the absence of H-donor.
(2)Electron-acceptor-bonded stationary phase, 3-(p-nitrophenoxy)propylsilyl (NPO), and electron-bonded phases, 3-(N-carbazolyl) propylsisly (CZP), 2-(1-pyrenyl) ethylsilyl (PYE), and 5-coronenylpentylsilyl (COP), were prepared from silica particles, and their selectivities were examined for PCDD isomers, hexachloronaphthalense (HxCNs), and planar and nonplanar PCB congeners. Although no single stationary phase was able to separate all the isomer pairs that are coproduced during the synthesis of the PCDDs and HxCNs, they can be separated by selecting a suitable stationary phase and solvent. The separation of PCDD isomers were found to be most successful with PYE and NPO phases. The two phases yielded the opposite elution orders for each isomer pair that is produced as a mixture. Similar results were obtained for the HxCN isomers that were separated on PYE and CZP phases. The COP phase provided easier separation of non-ortho-substituted and mono-ortho-substituted PCBs from the other PCBs based on the planarity than PYE phase. These stationary phases enabled total separation of all congeners of dioxins as well as group separation between PCDDs, PCBs, and PAHs.
(3)The possibility of isolating PCBs and PCDDs into an organic solvent upon deproteinization of a serum sample followed by the class separation of PCDDs from PCBs was shown by using a PYE silica column in addition to a restricted-access reversed-phase column packed with octadecylsilylated silica having diol functionality at the external surfaces. The first step solubilizes PCBs and dioxins from lipoproteins, and the second step provide group separations. The serum sample treatment method will allow shortening the preparation time from 24 h to about 1 h, by avoiding several chromatographic steps leading to cost and time efficient analysis by GC/MS.
The results suggest that sunlight photolysis of PCBs and PCDDs already released to the environment is potentially dangerous to living species, and that proper management and disposal of remaining PCBs are very important. The results also suggest that it is important to develop a more selective, sensitive, and rapid analysis method of these pollutants that needs minimum labor for the treatment of biological samples. The utilization of chromatographic techniques, or the use of solid surfaces for separation and decomposition of dioxins and PCBs is expected to lead to faster analysis and safer decomposition of environmental contaminants. Less
|
