環氧乙烷熱脫附採樣分析技術

The Sampling and Analysis Method of Ethylene Oxide by Thermal Desorption Technique

環氧乙烷（Ethylene Oxide, EtO）為各醫院所普遍使用的消毒氣體，亦是紡織與食品工業中常用的燻蒸劑。長期暴露在此工作環境下的作業者，會引起不良的健康效應，包括致癌性、中樞神經傷害、生殖危害、基因突變、及白內障等。由於法令對作業環境中環氧乙烷的容許濃度標準（PEL）要求日益嚴格，目前以活性碳管採樣／二硫化碳脫附／氣相層析儀分析之採樣分析技術，具有偵測極限偏高、溶劑毒性高及耗溶劑等缺點，因而發展一套方便、安全且可偵測較低濃度的採樣分析技術實有其必要。本研究即針對作業環境空氣中低濃度的環氧乙烷進行探討，嘗試利用熱脫附裝置將採集到的樣品脫附濃縮直接注入氣相層析儀火焰離子偵測器（GC/FID）中分析。空氣樣品的採集是利用低流量幫浦（流速60 mL/min）帶動空氣通過充填Carbosieve III吸附劑（600 mg）的採樣管，將環氧乙烷吸附捕集。分析程序首先是以100°C的溫度將採樣管中的環氧乙烷脫附出來，用液態氮將分析樣品冷凝濃縮於冷凝管，再以超高純度氦氣為載送氣體將脫附出來的環氧乙烷載送到氣相層析儀中，經長度為60m的Supelcowax 10層析 管柱分離後，以火焰離子偵測器（FID）對作業環境中之環氧乙烷進行定性、定量之分析。分析測定結果發現，熱脫附裝置的脫附效益可達100％，偵測極限值為1.2μg，樣品在-10°C冰箱中可穩定保存9天，故此採樣方法可應用於作業環境空氣中環氧乙烷之濃度測定。

Ethylene Oxide (EtO) is widely used to sterilize heat and moisture-sensitive materials in hospitals. It is also used as a fumigant in the textile and food industries. EtO is found to be a carcinogen, therefore, its permissible exposure level is lowered in recent years. It becomes necessary to develop new sampling and analytical methods of measuring EtO at low concentrations in order to estimate potential health effects from EtO in the occupational environment. This study is designed to develop a sampling and analytical method for measuring EtO exposures at ppm levels. We have successfully demonstrated that a sampling Carbosieve III sampling tube (600 mg) and a low-flow pump (60 mL/min for 6 hours) is able to collect enough amounts of EtO. The adsorbed EtO can be thermally desorbed by a thermal desorption unit and analyzed by a GC/FID system (HP5890). In analysis, EtO was first thermally desorbed atl00°C (Tekmar Inc., Model 6000) from Carbosieve and then cryogenically focused by liquid nitrogen at -150°C and finally carried into a 60m long Supelcowax 10 capillary column for separation and a flame ionization detector for identification and quantification. For EtO, the desorption efficiency of thermal desorber was 100%, the detection limit was 1.2μg, and the storage stability was 9 days at -10°C in the refrigerator.