甲苯被動式採樣熱脫附分析方法建立

A Passive Sampling and Thermal Desorption Method for Toluene Vapor

鑑於被動式採樣器具有質量輕、體積小、不須動力、不妨礙勞工作業等優點， 非常適合作業環境個人採樣：而熱脫附分析方法具有高靈敏度，無須前處理，無溶劑干擾分析，採樣管重複使用之優點。因此結合被動式採樣與熱脫附技術，進行甲苯被動式採樣熱脫附分析方法之測試，作為國內將來是否引進被動式採樣熱脫附技術於作業環境測定之先驅試驗。採用ATD不銹鋼採樣管，填充吸附劑Tenax-TA或Carbopack B，進行測試。於實驗室產生已知濃度的甲苯蒸氣，測試被動式採樣率。Tenax-TA採樣率約為1.85 ± 0.13 ng/ppm/min，Carbopack B 則為2.18 ± 0.06 ng/ppm/min。於0.10至0.41 m/s表面風速下，被動式採樣率不受影響，亦無方向性問題。隨著溫度之提高，採樣率略為增加，然未符合溫度理論推算之結果。用Tenax-TA採甲苯之採樣率於四小時後稍微下降，Carbopack B則能維持固定的採樣率。未發現逆擴散現象。於作業現場進行ATD採樣管被動式採樣與傳統活性碳管主動式採樣相互比較，雖有統計上偏差、然採樣濃度大致接近。最後撰寫甲苯被動式採樣熱脫附分析方法草案。

The combination of passive sampler and thermal desorption technique provides advantages such as light weight, small size, no power requirement went, low detection limit, no solvent interference and without pretreatment, etc. over conventional sorbent-desorption technique. Toluene was used as the test reagent to evaluate a passive sampling and thermal desorption method. ATD stainless steel tubes packed with Tenax-TA or Carbopack B were evaluated in laboratory by toluene vapor Uptake rate of Tenax-TA tube is about 1.85± 0.13ng/ppm/min, and it is 2.18±0.06 ng/ppm/min for Carbopack B tube. Surface velocity among 0.10 m/s to 0.41 m/s does not influence uptake rate. Sampling direction has no influence on uptake rate. The uptake rate increases with increasing temperature, but it is not consistent with thermal theory. After four hours sampling, the uptake rate of Tenax-TA tube decreased, however it remains constant for Carbopack B tube. No reverse diffusion was observed. ATD passive sampling tubes with thermal desorption and active sampling charcoal tubes with solvent desorption were compared in the field. Although statistical bias exists between them, the data from these three sampling tubes are consistent.