| 摘要: | 過氯酸根(Perchlorate, ClO4?)離子具有高穩定性，且因離子大小與碘離子相似，導致人體甲狀腺對碘離子的攝取受到干擾，因而被公認為美國及世界各地最關心的無機物污染議題。目前，愈來愈多發表的研究報告指出，在不同國家及各樣環境基質中，都有過氯酸根殘留的情況。過氯酸根可以被視為一種廣泛的環境污染物，然而在台灣有許多合法和非法煙火製作及施放情形，雖可能已受過氯酸根污染，但至今卻沒有獲到相關數據。 近來，中空纖維-液相微萃取(hollow-fiber liquid-phase microextraction, HF-LPME)技術已經被發展於水樣中多種有機污染物的萃取。HF-LPME將萃取、濃縮及樣品注入等步驟整合，提供一個迅速、簡單且價格低廉的樣品前處理技術。不過，HF-LPME還尚未被使用於水樣中無機污染物之萃取。 本研究主要利用離子配對-中空纖維-液相微萃取法對過氯酸根作定量萃取，並針對各個參數設定的影響(即萃取溶劑、離子對試劑種類及濃度、攪拌速度、萃取溫度與時間)進行有系統的研究與最佳化。過氯酸根離子配對後，可利用串聯質譜儀搭配直式電噴灑(tandem mass spectrometry coupled with direct electrospray, ESI-MS/MS)並以負離子游離模式進行定量分析。過氯酸根離子配對可被萃取於下述條件：在30 ?C及40分鐘下，使用60 ?L正辛醇(octanol)與離子對試劑5 mM正二己基醋酸銨(di-n-hexylammonium cetate，DHAA)於攪拌速度300 rpm進行萃取。偵測極限(limit of detection, LOD)為1 ?g/L (ppb)，而定量極限(limit of quantification, LOQ)則為3 ?g/L(ppb)。初步的結果顯示，在台灣收集到的飲用水與瓶裝水中沒有過氯酸根的殘留。不過，在非法煙火製造工廠的爆炸現場所附近收集到一些河水樣品中，利用標準添加法檢測，則有過氯酸根的殘留。這些樣品中，過氯酸根的濃度分別為6.3與130 ?g/L(ppb)，相關係數(correlation coefficient, r2) 分別為0.994 和0.999。由此所建立的分析程序，證明離子配對-中空纖維-液相微萃取法與直式的ESI-MS / MS方法為各種含微量過氯酸根的水樣樣品，提供了可靠、靈敏且方便的分析技術。 Perchlorate, ClO4?, is regarded as the most concerning inorganic contaminant in the USA and worldwide due to its high stability and interfering with iodide for uptake by the human thyroid because of their similar size. Currently, more and more reports have been published on the occurrence of perchlorate in different countries and various environmental matrices. Perchlorate can be considered as a widespread environmental contaminant. However, there is no data available in Taiwan, as there are many legal and illegal fireworks produced and set off in Taiwan, there could be perchlorate pollution in Taiwan. Recently, hollow-fiber liquid-phase microextraction (HF-LPME) technique has been developed to extract various organic pollutants from water samples. HF-LPME offers as a fast, simple and inexpensive sample preparation technique, which combines extraction, concentration and sample introduction into one step. However, HF-LPME has not been employed to extract inorganic contaminants from water samples. In this study, the effects of various operating parameters (i.e., extraction solvents, type and concentration of ion pair reagents, stirring speed, extraction temperatures and times) for the quantitative extraction of perchlorate by ion-pair HF-LPME were systematically investigated and optimized. Ion-paired perchlorate was then quantitated by tandem mass spectrometry coupled with direct electrospray (ESI-MS/MS) in negative ionization mode. The ion-paired perchlorate can be extracted by 60 ?L of octanol at 30 ?C with 40 min using di-n-hexylammonium acetate (5 mM) as the ion-pair reagent, stirring speed 300 rpm. The limit of detection (LOD) was 1 ?g/L and the limit of quantification (LOQ) was 3 ?g/L. Preliminary results show that no perchlorate residue was detected in the drinking water and bottle water samples collected in Taiwan. However, perchlorate residue was detected in some river water samples which collected near the explosion area of illegal fireworks via standard addition method. The concentrations of perchlorate in these samples were 6.3 and 130 ?g/L, and the correlation coefficient (r2) were 0.994 and 0.999, respectively. The analytical procedure developed herein demonstrated that the ion-pair HF-LPME and direct ESI-MS/MS methods are reliable, sensitive and offer a convenient analytical technique for trace determination of perchlorate in various water samples. |
