由於現今毛細層析管柱已發展成熟，化學作用力選擇多元且分離效率高，使得氣相層析儀（GC）成為分析大氣中微量氣體與揮發性有機化合物（VOCs）最為合適的方法。透過氣相層析儀串聯質譜儀（GC-MS）更可以鑑定出未知化合物結構，發揮定性與定量的效果。近二十年來，藉由全面二維層析（GC×GC）的快速發展，使得複雜樣品得以在二維平面上正交展開，層析峰峰容量因此可被大幅提升，成為近年來氣相層析方法上最大的突破亮點，而廣泛用於油品、香水、環境等領域需要使用強大分析鑑定能力的技術; 然而這項高解析分離技術卻鮮少在空氣污染研究上得到廣泛的應用，故本研究希望將GC×GC技術應用在空氣氣態樣品與PM2.5微粒上之VOCs化學成分鑑定工作上，將在過去基礎上持續開發全面二維層析串聯質譜儀（GC×GC/MS）之相關技術，期望能利用全面二維層析分離空氣以及氣膠中複雜化學成分，再以質譜儀鑑定關鍵化合物，以利於PM2.5排放源追溯以及光化演化過程之探討。在本計畫將針對PM2.5樣品發展出兩種分析方法，對於可揮發之VOCs部分，將以熱脫附(thermal desorption，TD)技術連接GC×GC/ToFMS系統成為TD-GC×GC/ToFMS技術，使分析物在進入氣相層析儀之前，藉由TD聚焦、濃縮，而使偵測極限降低3至5個數量級，達0.5 ppb以下; 同時亦將開發PM2.5濾紙溶劑萃取方法，將殘留在濾紙上低揮發性有機化合物萃取至溶劑中，經減容後再注入GC×GC/ToFMS中分析。目前在台灣，有相當大的研究資源投入於霧霾問題上，然而，卻缺乏適當的分析方法，使得氣膠的有機成份測定成果非常不足。因此，透過本計畫的努力將有機會改變現狀，以彌補氣膠科學所迫切需要填補的知識缺口。 ;Gas chromatography (GC) has been shown as a suitable technique to analyze atmospheric trace gases and volatile organic compounds (VOCs) due to high separation efficiency with the modern-day capillary columns of various chemical properties. The coupling of GC with mass spectrometry (MS) for detection makes compound identification unrivaled by other detection means. The advent of comprehensive two-dimensional GC (GC×GC) first appeared two decades ago takes the separation power to the next level by adding a second column to greatly enhance peak capacity of chromatography through orthogonal separation on a two-D surface. Due to its powerful separation capabilities, it has been widely used in petroleum, fragrance and environmental disciplines. However, this extremely powerful technique has not yet been widely utilized in atmospheric research to address issues of primary and secondary pollutants with relevance of health effect, surface ozone and PM2.5. Therefore, this project is aimed to develop novel GC×GC/MS techniques to analyze VOCs composition in ambient air and on fine aerosols at trace level. It is expected that key compounds identified by MS can provide useful information of source signature and advance knowledge of photochemistry. Two methods will be undergone development. To analyze ambient VOCs, thermal desorption (TD) will be coupled to GC×GC/ToFMS to allow enrichment prior to entering GC to enhance sensitivity by lowering the detection limit by an order of 3-5 to < 0.5 ppb (v/v). This method of TD-GC×GC/ToFMS will also be used to analyze filter paper of PM2.5 for the organic matter (OC). For the remaining organic matter of low volatility, solvent extraction will be performed before analyzed by GC/ToFMS. A fairly large portion of research resources has been devoted to aerosol studies in Taiwan to address the haze problem, however very limited effort by comparison is given to the organic composition of aerosols due to the lack of adequate methodologies. As a result, our effort can greatly change the status quo and fill the knowledge gap that is in dire need in the aerosol science community.
