利用固相微萃取技術發展空氣中臭氧之採樣分析方法

Abstract

在眾多空氣污染物中，臭氧為其中主要污染物之一，而當人們暴露其中時，可能會引起顯著的健康危害，例如：咳嗽、氣喘、頭痛及肺部疾病等。評估個人暴露於臭氧之方式很多，而被動式採樣器則是最常用的方法之一；然而大量有機溶劑之使用，則是現有方法的缺點。 固相微萃取技術(solid phase microextraction: SPME)結合了採樣、濃縮、及前處理等技術，也可以直接使用氣相層析儀分析，而這些優點是傳統分析法所沒有的。因此，本研究的目的即嘗試以固相微萃取技術採樣及分析空氣中之臭氧。 本研究以固相微萃取纖維poly(dimethylsiloxane)/divinylbenzene (PDBM/DVB)做為被動式採樣器之主體，並將1,2-di-(4-pyridyl)ethylene (DPE)吸附於纖維後，暴露於已知濃度之臭氧；纖維上所產生之pyriden-4-aldehyde，則以頂空萃取方式經吸附衍生試劑O-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA)後，在纖維上衍生形成oxime，並接著以可攜式氣相層析儀進行分析。研究中發現，經過7分鐘的熱脫附後，oxime的脫附效率可達百分之百而所設計之臭氧被動式採樣器之實驗採樣率為9.80×10-5±6.47×10-6 cm3/sec, 可偵測之最低濃度範圍為每小時120 ppb。本研究亦另外嘗試將DPE及PFBHA同時裹附於纖維後再進行採樣及分析；結果發現，除了將可節省實驗操作時間外，所得之實驗採樣率1.10×10-4±0.053×10-4 cm3/sec及可偵測之每最低濃度為每小時30 ppb。 與其他現有方法相比，本研究所發展的臭氧被動式採樣方法具有操作方便、可重覆使用及敏感度較高等優點；未來將繼續探討各種環境因素之影響，以進一步瞭解本方法使用上之限制。

Ozone is one of the major air pollutants and exposure to ozone might cause severe health effects, such as cough, asthma, headache, and lung diseases. To assess the exposures of ozone, several personal passive samplers are currently available. However, solvent desorption is commonly needed for the techniques which make the methods not very convenient. On the other hand, solid phase microextraciton (SPME) presents many advantages over conventional methods by combining sampling, preconcentration, and direct transfer of the analytes into a standard gas chromatograph (GC) system. Therefore, the purpose of this research was to develop a personal passive sampler for ozone based on the technique of SPME. Known concentrations of ozone were generated by the calibrated ozone generator in an exposure chamber. The poly(dimethylsiloxane)/divinylbenzene (PDBM/DVB) fiber was selected and 1,2-di-(4-pyridyl)ethylene (DPE) was first loaded onto the fiber. After exposures of ozone, pyriden-4-aldehyde was formed on the fiber and further headspace extraction of O-(2,3,4,5,6-Pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA) was then followed for the on-fiber derivatization. The derivatives, oximes, were then determined by portable gas chromatography/electron capture detection (portable GC/ECD) by directly inserting the SPME fibers into its injection port for thermal desorption and analysis. The desorption efficiency was found to be 100% when the time for thermal desorption time was 7 minutes while the experimental sampling rate was found to be 9.80×10-5±6.47×10-6 cm3/sec with detection limit of 120 ppb per hour. Other than the procedure mentioned above coating of PFBHA onto the fiber for the preparation of sampler before ozone exposure was also performed in the study. The results showed that the experimental sampling rate was 1.10×10-4±0.053×10-4 cm3/sec with detection limit of 30 ppb per hour. Compared with other methods, the current designed sampler provides a convenient and sensitive tool for the exposure assessments of ozone. More studies will be needed in the future to evaluate the possible effects of environmental factors on the designed sampler.