新穎大氣壓下有機質譜法之開發與應用

Abstract

大氣壓下質譜法的使用與發展最近很受到矚目，主要原因是因為樣品前處理步驟通 常可簡化或甚至可以省略，可將樣品直接放在大氣壓下就可進行分析，因此具有分析速 度快及容易操作等優點。我們最近發展了兩種新型大氣壓下質譜法：超音波輔助噴灑游 離質譜法及熱脫附大氣壓下質譜。前者是利用一超音波震盪器（頻率: 40 kHz）輔助樣 品分子之脫附游離，也就是將裝有樣品溶液之樣品瓶放入裝有水之超音波震盪器，而一 端拉尖之毛細管則放入樣品瓶中，拉尖一端則放置於靠近質譜進樣端，當超音波震盪器 打開時，樣品因超音波輔助震至毛細管尖端並在尖端產生樣品分子噴灑及游離化，產生 之離子可直接進到質譜中被偵測。而熱脫附大氣壓下質譜法則是利用一具可吸收近紅外 光之多層自組裝金奈米粒子玻璃片當作吸收雷射能量之基材，並且玻璃片可直接當作乘 載樣品之平台，波長808 nm 的近紅外光雷射對著鍍有多層金奈米粒子的一面進行照射， 則玻璃片另一面乘載的樣品分子會因為光轉熱效應進行熱脫附，熱脫附分子再即時經電 噴灑束進行後游離作用，產生之離子則可直接進到質譜中被偵測。在此計劃中我們就是 此兩種新發展之大氣壓下質譜法為基礎，進一步擴展應用這兩種質譜法於複雜樣品如高 鹽類之生物體液及有機反應產物之分析。在第一年的計劃中所將進行的實驗是探討熱脫 附大氣壓下質譜法於直接分析複雜樣品之可能性；而第二年之計劃目標為開發超音波輔 助噴灑質譜法於即時線上偵測超音波輔助有機反應產物之監測，所選擇的反應包括高分 子分解反應及轉酯化反應；而在第三年計劃中我們將發展可產生多支噴灑的超音波輔助 噴灑質譜系統，將其應用於線上除鹽及監測快速反應之實驗。

Ambient mass spectrometry (AMS) has lately attracted a great deal of attention because it allows for direct analyses at atmospheric pressure without any pre-treatment or with only a minimum sample preparation, offering the advantages of speed and ease-of-use. We recently explored two types of new AMS methods, i.e. ultrasonication-assisted spray ionization mass spectrometry (UASI) and thermal desorption AMS (TD-AMS). UASI MS employs a low frequency ultrasonicator (ca. 40 kHz) in place of the high electric field required for electrospray ionization. When a capillary inlet is immersed into a sample solution within a vial subjected to ultrasonication, an ultrasonic spray of the sample solution is emitted at the outlet of the tapered capillary, leading to the ready generation of gas phase ions. Additionally, layer-by-layer self-assembled multilayer of gold nanoparticle (Au NP)-based glass chip (Glass@AuNPs) with the absorption capacity in the near-infrared (NIR) region was used as the energy absorber and as the sample holder for sample deposition at ambient condition in TD-AMS. An NIR laser diode (808 nm) was successfully employed as the thermal desorption source to liberate only small molecules from Glass@AuNPs chips. The desorbed molecules are further ionized by post-ionization followed by the detection of a mass spectrometer. On the basis of these two new AMS methods, the applications in the analysis of complex samples including organic reaction products and high-salt biological fluids will be explored in this three-year project. In the first year of this proposal, it is aimed to employ the TD-AMS in the analysis of complex samples without sample pretreatment steps. The goal for the second year proposal is to explore a system based on the use of UASI MS for on-line monitoring ultrasonic-assisted organic reactions. Polymer degradations and transesterification reactions are selected as model reactions. In the third year of this proposal, a multi-spray UASI-MS system will be developed. The newly developed system is expected to have the capability of desalting during manipulating multi-spray in UASI MS. The possibility of monitoring reactions occurring during spray by multi-spray UASI MS will be also explored.