English  |  正體中文  |  简体中文  |  Items with full text/Total items : 66984/66984 (100%)
Visitors : 22944179      Online Users : 409
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Tips:
  • please add "double quotation mark" for query phrases to get precise results
  • please goto advance search for comprehansive author search
  • Adv. Search
    HomeLoginUploadHelpAboutAdminister Goto mobile version


    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5977


    Title: 大體積固相微萃取水中揮發性有機污染物;Large Volume Solid Phase Microextraction of Volatile Organic Compounds in Aqueous Sample
    Authors: 陳元曼;Yuan-Mam Chen
    Contributors: 化學研究所
    Keywords: 聚二甲基矽氧烷;大體積固相微萃取;非平衡狀態;large volume solid phase microextraction;poly dimethylsiloxane (PDMS);noneqilibrium condition
    Date: 2003-06-26
    Issue Date: 2009-09-22 10:11:20 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 固相微萃取(solid phase micro extraction;SPME)為近年來發展迅速之免溶劑萃取技術,目前也廣泛應用在許多液體樣品的分析上,SPME具有快速、省時、不需使用任何有機溶劑及符合經濟效率的優點,但有鑒於氣相層析儀(gas chromatography; GC)注射埠只能允許針筒插入進樣,因此商業化SPME必須以針筒方式設計。本實驗利用增加靜相的體積,以提高分析物的萃取量,以及利用SPME的概念自行塗佈poly dimethylsiloxane (PDMS)高分子薄膜,其成份接近於商業化SPME的吸附靜相,再配合自行研發之進樣裝置,使熱脫附分析物不再侷限於GC之注射埠,因此大幅降低偵測極限,唯塗佈上交聯過的PDMS 固相萃取棒熱脫附之後產生固定矽烷分子破片。 在實驗過程中自行設計了一套熱脫附進樣系統,再連續9次的分析50 μg/L(ppb)濃度之benzene、toluene、ethylbenzene、m-xylene、o-xylene (BTEX) 樣品,其再現性約達RSD 4%~12% 左右。與商業化SPME萃取裝置比較,在相同萃取條件下,自製大體積PDMS裝置無論對於標準樣品或真實水樣在層析圖譜上的表現幾乎完全相同但在感度表現上高出數十倍以上。另外,當未達平衡狀態,當實驗條件例如萃取時間、分析物之濃度及溫度均保持固定,被靜相所吸附之分析物量與其初始濃度,兩者間存在一比例關係,說明了當靜相體積固定,即使在非平衡狀態下,定量仍是可行的。根據此一簡單理論嘗試自行製作固相微萃取靜相,以增大靜相體積增加吸附量達到降低偵測極限外,也利用連續10次的重複萃取快速求得,GC所測得感度與每次萃取所存留一部分待測物而成指數下降函數,進而求得未知樣品之濃度。由此方法可知道,有些分析方法是可以完全迴避了製作檢量線的需求,不利用檢量線而也有很好的再現性,此一特點成為本研究最為獨特重點。 Sold phase micro extraction (SPME) has grown wide popularity in recently years in analyzing volatile or semi-volatile organic compounds in aqueous samples due to its ease of use, adequate sensitivity, solvent free in extraction, etc. The most attractive advantage with SPME over other means of extraction lies in the fact that no solvent is needed in the extraction procedure, the polymer phase coated on a thin fused silica fiber is employed as the extraction media to absorb organic analytes in aqueous samples. Subsequently, the fiber is inserted in the GC injection port to rapidly desorb the analytes onto the column. Assuming the volume of the polymer phase is negligible compared to that of the aqueous phase, the sensitivity of this technique is proportional to the volume of the polymer phase. Nevetheless, the geometry of regular GC injector forbids any forms of sample introduction other than needle type of insertion, as which the commercial SPME device is configured. To further lower the detection limit of SPME the injection port has to be redesign to accommodate a polymer phase of significant larger volume than the commercial SPME fiber. In this study, a thick film of polydimethylsiloxane (PDMS) polymer was coated on a glass rod of 5 mm O.D. x 5 cm length. A renovated thermal desorption device was designed and constructed to accommodate the thick PDMS rod. Furthermore, to avoid peak broadening in chromatography, a microtrap packed with chemical sorbents was employed to focus analytes desorbed from the large volume of PDMS, which resulted in comparable peak width but considerable peak height than the commercial SPME. Based on the analysis of standards containing 50 ?g/L of benzene, toluene, ethylbenzene, xylene and various true underground water samples, the self prepared large volume PDMS and accompanying device is several tens fold to 2 order of magnitude in sensitivity enhancement. We further employed the advantage of large volume PDMS extraction technique to develop a unique calibration method for BTEX based on the rapid exponential decrease in concentration from repeated extraction of a standard mixture. A linear relationship of log FID response versus extraction number was determined to be linear, which is consistent with the partition theory of extraction. Although the calibration was based on one standard mixture of unknown concentrations, the statistic risk arising from one-point calibration was minimized by the linear fitting of the numerous points generated by the multiple extraction procedure.
    Appears in Collections:[化學研究所] 博碩士論文

    Files in This Item:

    File SizeFormat
    0KbUnknown653View/Open


    All items in NCUIR are protected by copyright, with all rights reserved.

    社群 sharing

    ::: Copyright National Central University. | 國立中央大學圖書館版權所有 | 收藏本站 | 設為首頁 | 最佳瀏覽畫面: 1024*768 | 建站日期:8-24-2009 :::
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback  - 隱私權政策聲明