工業衛生上抽氣式霍氏紅外光譜偵測儀分析方法之研究

The Study on Extractive FTIR Analysis Method for Industrial Hygiene Evaluation

抽氣式霍氏紅外光譜偵測儀由於具備化合物辨識能力、靈敏度高、即時監測、可同時測得多種物質、電腦化數據處理等多項特點，故近來已被廣泛地應用於環境氣體監測。美國環保署已於1997年將抽氣式霍氏紅外光譜偵測儀列為測試方法，而美國國家職業安全衛生研究所也於1999年提出抽氣式霍氏紅外光譜偵測儀分析方法之草案，但由於其內容尚未完全發展成熟，且並未詳列標準檢測步驟，故於實際應用上尚有許多困難。有鑑於此，本研究係以US EPA Test Method 320：「有機及無機排放污染物抽氣式霍氏紅外光譜偵測儀量測方法」為藍本，參考美國環保署公告之Compendium Method TO-16：「周界空氣污染物開放光徑霍氏紅外光譜偵測儀量測方法」，並根據實際檢測經驗予以適度增修，提供制訂本土化標準檢測方法之內容。為評估抽氣式霍氏紅外光譜偵測儀量測技術之可行性，模擬同時存在多種氣體之作業環境，故本研究選擇不致相互反應之七種有機物作為研究對象。以甲烷、甲醇、氯仿、乙烯、丙酮、乙酸乙酯、六氟乙烷之混合氣體作為研究對象，測試項目包括解析度、雜訊、偵測極限、精密度、準確度及樣品添加。根據量測結果，FTIR對甲烷的偵測極限為3.5 ppm，其餘化合物之偵測極限皆可達到1 ppm以下，精密度皆小於2%，準確度大致上介於85〜110%之間，樣品添加回收率介於91〜115%之間。此外，依據研究結果建議日後之本土化標準檢測方法對於品保品管部分以精密度、準確度為主。

Extractive FTIR, a computerized technology with the advantages of real-time in-situ detection, great sensitivity, and identification power, has been widely used in gas monitoring. U.S. EPA had officially recognized the technique of extractive FTIR as Test Method 320 in 1997, U.S. NIOSH had also issued the draft of analysis method by extractive FTIR. However, those documents are not well developed and some important procedures are not given. Therefore, another standard method known as TO-16, which is much more specific but designed for open-path FTIR users, is also brought in to develop ROC standard method of extractive FTIR technology. To have a better understanding of this technique, an extractive FTIR system was tested with a gas stream containing methane, methanol, chloroform, ethylene, acetone, ethyl acetate and perfluoroethane. The characteristics of FTIR such as resolution, RMS noise, detection limits, precision, accuracy, calibration curve and sample spikes were studied. According to the results, the detection limits of 6 compounds were below 1 ppm except 3.5 ppm for methane. Precision was less than 2%, accuracy was among 85% to 110%, and recoveries of spike samples were between 91% and 115%. Besides, according to the result, It is recommanded that accuracy and precision should be the major part of the QA/QC program for the local standard method of extractive FTIR.