電流式微小氬氣電漿-氣相層析偵測器

Abstract

摘要 本實驗利用自行組裝的微型化介電質放電電漿應用於揮發性有機氣體分子的偵測，此微型化電漿偵測器是把不鏽鋼毛細管柱塞入玻璃管中密封後，並於玻璃管外纏繞電線製作而成。於電極兩端施加電壓9 kVp-p的高壓交流電後，可於常壓環境下形成穩定的電漿。本研究以氬氣作為載流氣體偵測訊號，當揮發性有機氣體通過電漿時，會和電漿中的氬離子發生反應，導致氬氣電漿的背景電壓值有明顯的變化。本研究進一步探討感測電極與電漿的距離、流速、電壓與反應訊號之間的關係，以找出在每一個不同變因下的最佳條件。當不同官能基的有機氣體分子，如烷類、醇類、酮類、酯類、芳香族；及鹵化物通過氬氣電漿時，皆有明顯的訊號變化。且訊號強度會隨著有機物碳鏈長度的增加而有逐漸增強的趨勢。本偵測器對iso-butanol的最低偵測下限為1.61 ng。此偵測器的優點為體積小、製作成本低，且有機氣體通過電漿時，訊號皆會有明顯的變化，因此可以應用於揮發性有機氣體的偵測。 關鍵字：介電質、常壓電漿、氣相層析

Abstract A self-assembly miniaturized dielectric barrier discharge plasma has applied for the detection of volatile organic gas molecules in this experiment. This miniaturized plasma detector was made by inserting a stainless steel capillary column into a glass tube and sealed it inside a glass tube, then tangled an electric wire around the glass tube. A high-voltage alternating current was applied on both electrodes, a stable plasma was generated under atmospheric pressure. In this experiment , we use argon as a carrier gas to detect signal. When volatile organic gas molecules passed through the plasma, they would reacted with argon ions in the plasma, caused an obviously change in the background voltage of argon plasma. This research further investigated the correlation of the distance between the electrode and plasma, flow rate and voltage to the response of detector ,to find the optimum condition in each variables. When organic gas molecules with different functional groups, such as: alkanes, alcohols, ketones, esters, aromatics and halide passed through the argon plasma ,they all caused an obviously change in the signal. And the intensity of the signal would gradually increased followed by the increasing of the length of carbon chain of organic compounds. The lowest detection limit of this detector for iso-butanol was 1.61 ng. This detector has the advantages of small volume, low cost, and would showed a significant change in the intensity of the signal when organic gas molecules passed through the plasma, therefore, it can be applied for the detection of volatile organic gas molecules. Key words：dielectric barrier、atmospheric plasma、gas chromatography