| 摘要: | 對-羥基苯甲酸酯( alkyl p-hydroxybenzoate, parabens) 對於細菌、酵母菌及黴菌有抑制效果，其成分無色、無味，價格又便宜，主要被添加於產品中做為防腐劑。Parabens不只用於化妝、保養品中，在藥品及食品中亦會添加。然而，少數人會產生接觸性蕁麻疹的問題，也有醫師在女性乳癌切片中發現parabens成分。但目前臨床上缺乏parabens會導致乳癌的直接證據，故歐盟未列管禁用。因環境基質複雜，濃度相對低了許多，因此，開發一套具有高選擇性的方法用以檢測環境中對-羥基苯甲酸酯的含量是不可或缺的趨勢。
分子拓印( molecularly imprinting) 是一種新興的技術可用於製備對特定化學分子具高專一性鍵結位置之材料。本實驗使用自組裝法，以氫鍵的方式將拓印的模板分子和官能基單體進行結合。以對-羥基苯甲酸乙酯( EtP) 作為模板分子、甲基丙烯酸( MAA) 為官能基單體、乙二醇二甲基丙烯酸酯( EGDMA) 作為交聯劑、偶氮二異丁腈( AIBN) 為起始劑，將其配製於溶劑中，與PVA水溶液混合，利用懸浮聚合法進行聚合反應，最後使用微波萃取將模板分子洗出，完成分子拓印聚合物( molecularly imprinted polymer, MIP) 製備。透過SEM觀察，確定其為微球狀高分子。
本研究利用製備出來的MIP作為分散式微固相萃取( dispersive micro solid-phase extraction, D-mSPE) 具選擇性的吸附劑，藉由分子拓印聚合物的高選擇性，將四種常見的parabens從環境水樣中萃取出來，並用氣相層析質譜儀檢測水樣中parabens的含量。
分子拓印分散式微固相萃取最佳化條件：50 mg的吸附劑與40 ml真實樣品進行超音波震盪，再將其抽氣過濾取得乾燥之吸附劑，以400 μl甲醇反萃取之，再進到GC-MS進行檢測。在0.2-10 μg/L的濃度範圍內，檢量線決定係數R2皆在0.991以上；偵測極限( LOD) 為0.050-0.060 μg/L。在精密度與準確度的測試，其相對標準偏差( RSDs) 皆小於8%，顯示此方法具有良好的穩定性及再現性。在水樣中測得的parabens濃度介於0.36-9.42 μg/L之間。
;Alkyl p-hydroxybenzonates( parabens) are highly effective in preventing the growth and spread of bacteria, yeast, and mold. On account of the fact that they are colorless, tasteless, and relatively cheap, parabens are applied to serve as preservative in cosmetics, care products, pharmaceuticals, and foods. On the other hand, a minority of parabens has been shown to cause Contact Urticaria, and parabens has been linked to breast cancer in females. Since direct evidence for parabens causing breast cancer has not been found, however, parabens are not listed in restricted items by the European Union. In the complex matrix of everyday environment, concentrations of parabens are relatively low. As a result, it is important to develop a set of highly selective detection method for parabens in the environment.
Molecular imprinting is an increasingly popular technology for the preparation of specific molecular material with highly selectivity bonding sites. In this study, a self-assembly approach was used. The templates are combined with functional monomers by hydrogen bonds. Ethyl p-hydroxybenzonate( EtP) was used as the template, methylacrylate( MAA) as the functional monomer, ethylene glycol dimethacrylate( EGDMA) as the cross-linker, and azobisisobutyronitrile( AIBN) as the initiator. Together, these chemicals were prepared and mixed with polyvinyl alcohol( PVA) solution and polymerized with suspension polymerization. As the final step, microwave extraction was used to remove the template. The MIP was confirmed as a microspheroidal polymer by scanning the product with an electron microscope.
In this study, MIP was utilized as the selective absorbent of dispersive micro Solid-phase Extraction( D-m-SPE). Four common parabens were extracted from environmental water samples by the high selectivity of MIP, then the identity of the content was determined using Gas chromatography – Mass spectrometry( GC-MS).
The following are optimization conditions of the D-m-SPE: 50 mg of MIP absorbent and 40 ml of real water sample were oscillated by an ultrasonic bath. Next, dry absorbent was obtained by vacuum filtration and back-extracted with 400 μl methyl alcohol. Finally, the obtained solution was injected in GC-MS for detection. In linear range of 0.2-10 μg/ml, the regression coefficients R2 were all above 0.991; the limit of detections ( LOD) were within the range of 0.050- 0.060 μg/ml. The relative standard deviations( RSD) were less than 8% by tests of precision and accuracy. The results showed the stability and reproducibility of this method. The total concentrations of these four parabens in various water samples from Taiwan were ranged from 0.36 to 9.42 μg/L. |
