開發線上萃取及採樣方法以質譜分析有機揮發物質

基礎化學知識為分析科學中的基石。除此之外，分析裝置與設備的開發也被視為同等重要，因其對於可靠數據之蒐集與分析表現的穩定程度有所助益。也因此，我們專注於自動化裝置的開發以及分析表現的測試。在第一項研究中(章節二)，我們提出了一個將液態基質中的揮發和半揮發物質快速萃取至氣相的方法。此方法利用加壓後溶於溶液中的氣體與攪拌功能來實現。萃取腔室中的瞬間洩壓會導致冒泡現象的產生。於此過程中，大量氣泡於液體基質中形成。在這短短時間內(幾秒內)，溶解於溶液中的氣體與揮發性物質皆被釋放到腔室的頂空當中。而萃取過後的頂空氣體立即的被送至偵測儀器；在此研究當中，偵測器為大氣壓力化學反應游離法之三段四極柱質譜儀。此裝置的特性提供了一項可快速偵測與定量存在於液體基質中揮發與半揮發性物質的方法。我們也證實了氣泡萃取裝置適用於多種複雜基質中揮發性物質的萃取。在第二個計劃中(章節三)，我們建立了一個雙腔室採樣系統，並將其與質譜儀聯用。生物性試樣被置入氣密式的腔室中，並定時的通入載氣，將存在於腔室頂空的揮發性有機物質遞往三段式四極柱質譜儀之大氣壓化學反應游離介面。於每個生物試樣之氣態分析物的進樣時間點前，來自空白腔室的控制組質譜圖會優先被記錄，如此一來便提供了訊號之間的比對及雜訊的刪減。我們首先使用標準樣品來測試此項自動化的雙腔室採樣系統之分析性能，再以其來及時偵測釀酒酵母的生長、珊瑚菇的子實體化，與太平洋白蝦的腐化過程。在不同的生長與腐化階段所偵測到的揮發性有機物呈現了峰型或高原型的時間解析輪廓。

關鍵字

揮發有機物質；自動化；氣泡萃取；質譜法；微生物代謝物；即時分析

並列摘要

The knowledge of basic chemistry is the foundation of analytical science. In addition, development of instrumental tools is required to provide adequate conditions for chemical analysis. In this project, we focused on the development of new analytical instruments, and characterized their performances. In the first project (Chapter 2), we propose a new method for fast extraction of volatile organic compounds (VOCs) from liquid matrices. This method involves dissolution of a carrier gas in the liquid sample by applying a moderate overpressure ( 150 kPa), and stirring the sample. An abrupt decompression of the extraction chamber leads to effervescence. In this step, many bubbles are instantly formed in the sample matrix. The dissolved carrier gas as well as dissolved VOCs are liberated into the headspace of the extraction chamber within a short period of time (few seconds). The gaseous effluent of the extraction chamber is immediately transferred to the on-line detector; in this case, an atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. This feature provides the means to detect and quantify analytes present in solutions in a short period of time. We show that fizzy extraction is suitable for analysis of volatile/semi-volatile compounds present in various samples, including those containing complex matrices. In the second project (Chapter 3), a dual-chamber sampling system has been constructed, and coupled on-line to mass spectrometry. The biological specimen is placed in a gas-tight sampling chamber. A carrier gas is introduced to the chamber periodically to transfer the VOCs present in the specimen headspace to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. A control/blank spectrum is recorded before recording specimen spectrum at each time point, enabling signal comparison and subtraction. The automated dual chamber sampling system was first tested using standard mixtures to verify its analytical performance. We subsequently implemented it in real-time monitoring of the growth of baker’s yeast (Saccharomyces cerevisiae), fructification of golden oyster mushroom (Pleurotus citrinopileatus), and microbial degradation of Pacific white shrimp (Litopenaeus vannamei). The recorded VOC signals show characteristic temporal profiles with transient bands or plateaus corresponding to different stages of microbial growth and putrefaction processes. Overall, this thesis describes two newly developed systems for fast extraction and sampling of VOCs for mass spectrometric analysis with little human intervention.

並列關鍵字

volatile organic compounds ； automation ； fizzy extraction ； mass spectrometry ； microbial metabolites ； real-time analysis

參考文獻

1. Volatile Organic Compounds (VOC). Luxembourg: Eurofins Scientific. Available at: https://www.eurofins.com/voc.aspx. Retrieved Jul 03, 2012. (accessed August 24, 2018)