以微波萃取方式萃取空氣中之粒狀及氣狀PAH汙染物之最佳條件建立與應用

Optimization and application of a microwave-assisted extraction method for analysis of polycyclic aromatic hydrocarbons in airborne particles and gases

沈文弘(Wen-Hung, Shen)

指導教授 ： 彭瓊瑜

高雄醫學大學/健康科學院/職業安全衛生研究所/碩士(2012年)

https://doi.org/10.6832/KMU.2012.00005

摘要

多環芳香烴化合物(Polycyclic Aromatic Hydrocarbons，PAHs)是環境中常見汙染物，PAHs主要來自人為活動，如工業、交通廢氣與烹煮時的油煙，以粒相 (particulate phase)與氣相 (gas phase)存在於環境，因此評估PAH濃度與危害時需同時捕集兩種狀態的PAHs；而在分析前，需將PAHs從介質上脫附，因此萃取方法好壞是正確評估PAH暴露量之關鍵；現今仍以索氏萃取(Soxhlet extraction)為主，此法需大量溶劑 (solvent)與較長的萃取時間(extraction time)才能得到良好的回收率 (recovery rate)，萃取後又須去除多餘溶劑，增加環境危害與操作人員的負擔。微波萃取法 (microwave-assisted extraction，MAE)只需少量溶劑與較短的時間，即可將污染物由環境或採樣介質萃取出，然而此萃取的方法較少用於採樣介質的萃取，其與索氏萃取的比較結果闕如，因此本研究目的為：1.針對MAE建立最適萃取條件。2.比較MAE與現行兩種萃取方法 (Soxhlet &超音波萃取, (USE) )的效率。3.將MAE應用於實際採樣之油煙樣本與廢氣樣本。本研究捕集氣狀及粒狀PAHs之採樣介質分別為XAD-2管與鐵氟龍(Teflon)濾紙。添加PAHs標準品於上述兩種介質，經萃取分析後，與添加質量比較，計算出回收率，以了解方法萃取效率。此外，本研究加入positive control，目的為排除脫附因素，實際了解萃取過程中之損失情況。
依據本研究結果，MAE的最適條件為：溶劑選用13毫升的丙酮與正己烷混和液 (1:1，V/V)，萃取時間為15分鐘，濾紙與XAD-2的回收效率範圍分別為1.76 % ~ 121.95 %與16.39 % ~ 91.79 %。三種萃取方法中，濾紙萃取方面，以MAE萃取效率最好，Soxhlet次之；而在XAD-2管方面，低分子量PAHs以USE萃取效率最好，MAE次之，但在高分子量PAHs則是以Soxhlet最好，MAE次之。由結果得知，MAE不需耗費時間與大溶劑，就可達到與Soxhlet相近之萃取效果。在實際樣本萃取方面，油煙樣本粒相PAH重量濃度範圍為0.005 ~ 12.737 μg/m3，氣相則是0.043 ~ 24.367 μg/m3，在廢氣樣本之粒相PAH重量濃度範圍為0.001 ~ 2.014 μg/m3，氣相則是0.005 ~ 5.762 μg/m3，與其他相關文獻一致，表示本研究所建立之方法可應用於實際採樣，且能有效降低溶劑使用量與萃取時間。

關鍵字

微波萃取 ； 多環芳香烴化合物 ； XAD2 管 ； 鐵氟龍濾紙

並列摘要

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants which are mainly from anthropological sources, such as industrial exhaust, traffic exhaust and cooking oil fumes. Therefore, PAHs were intensively investigated in terms of concentration distribution, exposure assessment, and health effects. PAHs are present in airborne particulates and gaseous phases and many kinds of environmental media, such as dust, sediment and soil. Currently, Teflon filters and XAD-2 tubes are used to collect particulate- and gas- PAHs, respectively. Before analyse, PAHs should be extracted from samples or environmental media. Therefore, extraction is a critical step for accurate estimation of PAH exposure. Traditionally, Soxhlet extraction is used for the extraction of ambient samples, but it requires very long extraction time and large amounts of solvent. Microwave-assisted extraction (MAE) only needs a few milliliter solvent and a couple of minutes to extract pollutants from media. However, this method is not widely used, and few studies compare this method to the traditional methods, such as Soxhlet extraction and ultrasonic extraction (USE). There are three objectives of the present research: 1. Optimization of a microwave-assisted extraction method for PAHs sampling media (Teflon filters and XAD-2 tubes). 2. Comparison of two frequently used extraction methods to MAE in terms of extraction time, consumed solvent volumes, reproducibilities and recovery rates. 3. Application of this microwave-assisted extraction method in real ambient PAH samples.
Based on this study’s results, the optimal conditions are 13 mL of acetone/hexane (1:1) solvent mixture, and an extraction program of room temperature to 115℃ in 15 minutes, then holding for 15 minutes. Ranges of recovery rates of filter and XAD-2 are 1.76 % ~ 121.95 % and 16.39 % ~ 91.79 %. In method comparison, MAE’s recovery rate is better than USE and Soxhlet extraction for filters. For XAD-2 tube, the recovery rates of low molecular weight PAHs in descending order are USE > MAE > Soxhlet, while the recovery rates of high molecular weight PAHs in descending order are Soxhlet > MAE > USE. Although MAE only has moderate recovery rates at XAD2 tube, MAE has characteristics of shorter extraction time, few amont of extraction solvent, and good recovery rates at filters.
It is comparable to traditional extraction methods in terms of recovery rates. MAE also provides good efficiency in extraction of real ambient samples, the range of particulate PAH concentration of cooking oil fume is 0.005 ~ 12.737 μg/m3, gas-PAH is 0.043 ~ 24.367 μg/m3. In exhaust sample, the range of particulate PAH concentration is 0.001 ~ 2.014 μg/m3, gas-PAH is 0.005 ~ 5.762 μg/m3. Therefor, it is a promising extraction method and can be applied for varities of sampling or environmental media.

並列關鍵字

Microwave-assisted extraction ； Polycyclic aromatic hydrocarbons ； XAD-2 tube ； Teflon filter

參考文獻

Agency for Toxic Substances and Disease Registry. (2012). Case Studies in Environmental Medicine Toxicity of Polycyclic Aromatic Hydrocarbons (PAHs)

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