以固相微萃取技術搭配動態非平衡暴露系統進行空氣中三氯氨採樣之方法開發

Abstract

三氯胺是一個具有高揮發性的消毒副產物。在游泳池環境中，它可能會由來自人體的有機氮源與氯反應而生成。文獻資料顯示，兒童和成年人均有可能因為暴露三氯胺而導致相關的急慢性健康效應。評估空氣中三氯胺濃度的方法中，現行常用的方法需要使用採樣幫浦，並且過程包含極為複雜的樣本前處理及分析流程，使得三氯胺的暴露評估相當不便。而另一方面，固相微萃取（SPME）的方法則有相對較多的使用優點，因此，本研究的目的即為開發一以SPME做為採樣工具並搭配動態非平衡系統的三氯胺採樣方法。 三氯胺的製備是由混和次氯酸鈉與氯化銨而成。在動態非平衡氣體產生系統中，氯胺氣流會通過洗滌瓶來去除可能帶來干擾的化學物質，例如一、二氯胺。通過的三氯胺氣流會被導入暴露腔中進行接下來的採樣動作。在本研究中，我們以兩種採樣方法進行分析。第一種是以固相微萃取技術（SPME）搭配纖維上衍生反應做三氯胺的採樣分析。首先會在纖維上裹附衍生試劑－環己烯，接著再放入動態暴露腔中進行三氯胺採樣，衍生物－一氯環己烷便會在纖維上生成。第二種方法則是以SPME做三氯胺的直接暴露萃取。兩種方法均以氣相層析質譜儀作為後續的分析儀器。 實驗發現Carboxen/PDMS SPME纖維具有最好的萃取效率，並能最穩定地保存纖維上的分析物。在非平衡狀態下分別進行有無衍生反應的三氯胺採樣，經不同的暴露量值（濃度×時間）的環境條件測試，所計算得到的實驗採樣率分別為：7.93×10-6 cm3/s（有衍生）及0.1032 cm3/s（無衍生）。 此研究結果顯示，以動態非平衡暴露系統進行SPME的三氯胺採樣之方法提供了未來應用於偵測游泳池空氣品質的潛在可行辦法。然而，本研究方法應用於低環境濃度下可能有偵測敏感度下降的限制，未來需要更多低濃度環境的採樣率驗證。

Nitrogen trichloride (trichloramine; NCl3) is a highly volatile disinfection by-product. In swimming pools, it is possibly formed when organic nitrogen sources from visitors react with chlorine. Acute and chronic health effects have been observed in both children and adults exposed to NCl3. To monitor the concentrations of NCl3 in air, current available method employed sampling pump and required complicated sample preparation and analysis procedure which makes it uneasy to assess the exposures. On the other hand, solid phase microextraciton (SPME) presents many advantages over conventional analytical methods. The aim of this research was then to develop a sampling method for NCl3 under nonequilibrium condition based on the technique of SPME. NCl3 was prepared by mixing sodium hypochlorite with ammonium chloride and was further injected into the designed gas generation system. The air flow was then washed in scrubbers to trap the potential interfering compounds, such as mono- and dichloramine, which might also be formed in the reaction. Afterwards, the air flow was directed into the sampling chamber. There were two sampling approaches. The first was conducted using on-fiber derivatization. SPME fiber, which was first coated with cyclohexene, was exposed to NCl3 to perform on-fiber derivatization. Chlorocyclohexane was then formed as the derivative. The second approach was to sample trichloramine directly using SPME fiber. Both approaches were followed by the analysis with gas chromatography/mass spectrometry. It was observed that Carboxen/PDMS SPME fiber provided the best extraction efficiency with the highest sample-holding stability. The sampling of NCl3 under nonequilibrium condition with/without on-fiber derivatization was performed. Several magnitude of exposure (NCl3 concentration × sampling time) were tested and the experimental sampling rates of NCl3 were found as follows, 7.93×10-6 cm3/s (with on-fiber derivatization) and 0.1032 cm3/s (without on-fiber derivatization). The designed method demonstrated the potential of applying SPME technique under non-equilibrium condition for NCl3 sampling which could be applied in monitoring the air quality of swimming pools in the future. However, there is limitation such as the decreasing of detection sensitivity under low environmental concentration. Further validations on the sampling rates under low NCl3 concentration should be performed.