無接觸式大氣壓下游離質譜法之發展與應用

Abstract

質譜法目前已經成為強大的分析工具，近年來大氣壓下質譜游離技術的蓬勃發展，突破在真空下操作的限制，只需些許或不需要樣品前處理等繁瑣步驟，已拓展了質譜法的應用範圍。而到目前為止所發表的大氣壓力游離法皆需輔助裝置如高電壓、加熱器、雷射及氣體輔助噴灑等等來幫助樣品游離，本論文的目標為發展一簡易的大氣壓下游離質譜的技術，簡單利用拉尖毛細管(~1 cm)與鋁板承載盤，成功的設計出非常簡單和容易操作與組裝的新型質譜游離裝置。本實驗裝置的特色就是不需要任何的輔助裝置，利用拉尖的毛細管本身的毛細現象，使得載盤上的液態樣品中，能從進樣端將樣品送至噴灑尖端，由於毛細管尖端放置在非常接近質譜進樣端，靠著質譜內電場作用使毛細管尖端產生極化效應造成電荷累積在尖端，造成前端液珠因承受不了液滴內的庫倫排斥力造成液滴爆破而產生之微小液滴會含有一定電荷數，最後在溶劑揮發下，最後只剩下帶電荷的分析物離子進入質譜進行分析。由實驗結果可證實無接觸式大氣壓力下游離質譜法之發展與應用可以用於分析具小分子量的胺基酸至大分子量的蛋白質樣品。並由訊號強度、訊雜比和機制的討論，確認與電噴灑游離法兩者之間的差異性。除了針對液態樣品的分析之應用如複雜樣品，細胞的萃取物及尿液的分析外，也針對含水量高的水果樣品和在飲品中塑化劑進行分析，除了定性分析外，本論文也以三聚氰胺為樣品探討本方法之定量能力。而實驗中也嘗試固體樣品之分析，選用樣品包括市售藥丸、咖啡豆和黏度較高的果糖液體，針對水果表皮殘餘農藥進行偵測和農藥標準品的定量。 除了一般分析物之分析外，本論文也嘗試使用此新型大氣壓下質譜游離法於線上即時偵測有機反應及光催化反應，實驗結果顯示本方法是相當適合用於即時監控化學反應進行的方法。從本論文所得結果顯示，此無接觸式大氣壓下質譜游離法具有簡單、易操作和使用範圍廣泛之優點和潛力，有機會進一步擴展它在化學及生物領域的應用範圍。

Mass spectrometry (MS) is a powerful analytical tool and the MS ionization source continues to drive technical innovation for the detection of analytes. The ionization methods have represented a breakthrough technology that is not restricted to operation in a vacuum. Direct analysis of samples at atmospheric pressure with little or no sample pre-treatment is the trend for the development of ambient MS, which has expanded further the applications of MS in different research fields. Currently, the atmospheric pressure ionization (API) methods require additional accessories to facilitate the ionization process. In this thesis, a very simple ionization method is explored. The setup consists of only a few easily attainable and inexpensive components. A short tapered capillary is used to drive liquid samples from the microscale reservoir toward the outlet. Fine droplets form at the tapered tip positioned in the proximity of the MS orifice. Because of the capillary action, continuous flow of the sample towards the tapered end of the capillary is generated, followed by an immediate phase change in the analytes from liquid to gas. The method is so called contactless API (CAPI). On the basis of the experimental results, a wide range of analytes in either simple solutions or complex matrices can be analyzed. Single and multiply charged ions can be detected in either positive or negative-ion mode. The signal strength, signal to noise ratio, and mechanisms of CAPI were compared with those in conventional electrospray ionization (ESI). In the analysis of liquid samples, CAPI is shown to be suitable for the analysis of cell extracts, urine, and juice contained in the fruit samples, plasticizers in drinks, and for quantitative analysis of melamine in aqueous solution. CAPI is suitable for solid samples, such as pills, coffee beans, and highly viscous fructose. It can also detect and quantify the pesticides on the fruit epidermis. This method can be automated to not only analyze a variety of small molecule compounds, but also real biological samples. It can quickly analyze a large number of samples for quantitative analysis. A calibration curve can be constructed by using the ratio of the analyte peak area to that of internal standard versus the analyte concentrations. Another application is doing real-time online monitoring of chemical organic reactions and photocatalytic reactions. Parameters for optimization, such as flow rate, voltage, material of vial were discussed. On the basis of our experimental results, we conclude that not only is CAPI simple, disposable, and low cost, but also it has the potential for more applications in the chemical or biological fields in the future.