作業環境空氣中氯乙烯之採樣分析

Sampling and Analysis of Vinyl Chloride in Workplace Air

氯乙烯為目前使用相當廣泛之塑膠聚合物－聚氯乙烯的單體原料。人體的主要暴露途徑為經由呼吸道之進入。氯乙烯為一種人體致癌物。目前作業環境空氣中氯乙烯濃度的限制值有美國職業安全衛生署所規定之1 ppm為時量平均容許濃度及美國政府工業衛生技師協會所訂之5 ppm為容許濃度標準。我國行政院勞委會則規定10 ppm為容許濃度標準。現有偵測作業環境空氣中氯乙烯的標準方法為我國行政院勞委會制定之『作業環境空氣中有害物質標準分析參考方法2306』。此法以活性碳採集空氣樣品，再添加二硫化碳萃取後取少量注入氣相層析儀分析。二硫化碳為易燃且有毒之有機溶劑。而且此方法操作步驟繁瑣，其靈敏度又受限於注射量少而不佳。本研究以熱脫附氣相層析法直接分析樣品，改善了溶劑萃取法之缺點，而達到對分析方法之安全、方便、經濟、快速及可靠的要求。

Vinyl chloride is a monomer for making widely-used plastic material polyvinyl chloride. The major route of exposure to human is through the respiratory system. Vinyl chloride is a recognized human carcinogen. Current PEL value of 1 ppm is adopted by OSHA and 5 ppm is recommended by ACGIH in the U.S. The PEL value of 10 ppm is adopted by Council of Labor Affairs, Executive Yuan, R.O.C. The method 2306 is a standard method used for sampling and analysis of vinyl chloride in workplace air. This method used charcoal tube to take air sample. Carbon disulfide is added to the charcoal to extract vinyl chloride. A few μl of solution is taken and injected into the GC for analysis. Carbon disulfide is known for its flammability and toxic property. The method is tedious and less sensitive because only a small aliquot is used for analysis. The thermal desorption gas chromatographic method can analyze sample directly and eliminate many of the disadvantages of solvent extraction method. The method is safe, convenient, economic, fast and reliable.