多層金奈米粒子晶片結合近紅外光雷射於大氣壓力質譜法游離源之開發

Abstract

自J. J. Thomson提出質譜法的概念，開啟質譜學研究的大門以來，質譜法儼然已經成為目前各類研究上一強而有力的鑑定工具。過去一世紀，質譜游離技術不斷地推陳出新，本世紀初，一種引人注目的新式質譜法應運而生，即大氣壓力質譜法；大氣壓力質譜法的開發突破以往必須在真空下操作的限制，省去樣品前製備及樣品前分離等手續，能直接於大氣壓力下對分析物進行分析，加快了分析速度。

本篇論文主要是根據現有的大氣壓力質譜法設計基礎，提出另一種新式熱脫附技術。以逐層自組裝的方式製備出來之多層金奈米粒子晶片，具有金奈米粒子固有的特殊侷域性表面電漿共振性質，並透過金奈米粒子間偶極-偶極作用力，而使多層金奈米粒子晶片於近紅外光區 (~808 nm) 具有電磁波譜吸收，而能做為吸收該波段能量之光熱轉換基材並輔助樣品進行熱脫附。同時選用造價低廉的連續式近紅外光偶極雷射 (808 nm) 做為熱脫附源，照射乘載有分析物之晶片背面，晶片能透過光熱效應而使表面溫度上升，達到將分析物熱脫附成氣態分子離子之目的，並借助後游離源的加入，提高游離效率，使分子離子進入離子阱質譜儀而被偵測到，其中後游離源是為拉尖的短毛細管電噴灑界面，以含有0.1% 醋酸的乙腈水溶液做為電噴灑溶劑。

經由實驗證實，此新式脫附游離技術適合分析極性小分子，包括小分子有機酸、胺基酸及殺蟲劑，不需要繁複的前處理，即能成功地透過近紅外光雷射輔助系統由複雜血清樣品中偵測到分析物訊號。整體而言，此方法是一相當簡單且容易操作的大氣壓力質譜法。

Since J. J. Thomson proposed the concept of the mass spectrometry, mass spectrometry has become one of the most powerful analytical tools. In the past century, ionization methods have made dramatic progress. In the beginning of this century, a new-class mass spectrometry, i.e. ambient mass spectrometry, allows for direct analysis at atmospheric pressure with minima sample preparation, has attracted much attention.

In this thesis, a new thermal desorption based ambient mass spectrometry was proposed. A multilayer of gold nanoparticle glass chip (Glass@AuNPs) having localized surface plasma resonance (LSPR) in the near infrared (NIR) region (~808 nm) of electromagnetic spectrum arising from dipole-dipole interactions between the gold nanoparticles was used as the photothermal substrate and for sample deposition. An inexpensive diode laser (808 nm) was used as the source to irradiate the rear side of the Glass@AuNPs for assisting thermal desorption of small organics. Gaseous analyte ions can then be monitored by an ion trap mass analyzer after post ionization, which was assisted by generating electrospray of deionized water/acetonitrile containing 0.1% acetic acid from a short tapered capillary.

This approach was suited to the analysis of small polar organics including small acids, amino acids, insectides, and pesticides. Without sample pretreatment, analytes in complex serum samples can be readily observed in the NIR laser-assisted mass spectra. The main advantage of this approach is its simplicity and ease of operation.