Tenax-TA熱脫附分析方法驗證與現場應用探討

Validation Tests and Field Application Considerations of the Tenax-TA Thermal Desorption Method

熱脫附/氣相層析儀方法為近來大氣環境採樣分析的趨勢，本研究針對Tenax-TA 所能吸附之化合物，包括乙酸乙酯、1,2-二氯乙烷、三氯乙烯、甲基異丁基酮、乙酸第二丁酯、甲苯、乙酸正丁酯、四氯乙烯、二甲苯、對-苯乙烯及酚等11 種化合物，進行熱脫附分析方法驗證。測試項目包括，熱脫附溫度、管線溫度與閥溫度測試，冷凝捕集溫度與加熱時間之測試，氣相層析儀條件測試、熱脫附效率測試、檢量線範圍測試、分析變異係數測試及盲樣測試等。並蒐集採樣資料，探討適合作業環境使用之採樣條件。本研究建立之熱脫附分析條件為熱脫附溫度280℃、脫附時間10 分鐘，管線與閥溫度150℃。Tenax-TA 採樣管熱脫附效率良好（99%以上）；分析再現性佳（變異係數<3.4%）；檢量線線性範圍廣（至少100 倍）且相關係數高（r>0.995）；盲樣測試偏差，除酚為15%外，其餘化合物皆在10%以內。從實驗得知，熱脫附/GC/FID 分析方法為一自動化、偵測靈敏度高、便利可靠之分析方法，非常適用於環境監測。依蒐集之採樣資料，熱脫附分析方法應用於濃度較高之作業環境測定，主動式採樣體積最好不超過2.5 L，且每支採樣管採集之化合物不超過1 mg。若為被動式採樣，則較無破出之疑慮。在室溫下，樣品儲存穩定期限約為二週。

Thermal Desorption/Gas Chromatography method is popularly used in atmosphere sampling and analysis in recent years. This study is to validate Tenax-TA thermal desorption method for 11 compounds’ simultaneous analysis. The tested compounds include ethyl acetate, 1,2-dichloroethane, trichloroethylene, methy isobutyl ketone, sec-butyl acetate, toluene, n-butyl acetate, tetrachloroethylene, p-xylene, styrene and phenol. Validation tests include thermal desorption temperature, line and valve temperature, cold trap temperature and heating time, gas chromatography analysis conditions, thermal desorption efficiency, calibration linear range, analytical variation and blind sample tests. The thermal desorption temperature is 280℃ for 10 minutes and both line and valve temperatures are 150℃. The results indicate that Tenax-TA tube has good thermal desorption efficiency (>99%) for these 11 compounds, analytical variations are acceptable (CV<3.4%), calibration linear range is wide (at least 100 times) with good correlation coefficient (r>0.995) and the bias of blind sample analysis is below 10% except phenol (15%). From experiments, thermal desorption/GC/FID is an automatic, highly 3 sensitive, convenient and reliable method for environmental monitoring. From literature review, thermal desorption method has limited sample volume (about 2.5 L) for workplace environmental monitoring, and each tube should not exceed 1 mg of analytes. However, passive sampling with low uptake rate has an 8-hour sampling capacity without breakthrough. The sample storage time is about two weeks at room temperature.