ABTS•+(2,2’-azinobis-(3-ethylbenzothiazoline-6- sulfonate acid) radical cation)去色分析不僅被廣泛地使用在抗氧化能力分析上,自從ABTS•+與層析分離技術結合後,對於環境分析領域相關的應用更具重要價值。本研究主要的目的為提供一個線上產生ABTS•+試劑作為CZE後衍生系統用以分析樣品抗氧化能力。本實驗利用UV 254 nm光源直接光解ABTS產生非常穩定的ABTS•+,並嘗試建立一套線上光氧化裝置,利用PTFE tubing線圈形成流動式光反應器(flow-through photoreactor)作為後衍生分析系統。此系統除了可簡化操作程序,還可以快速地在線上產生ABTS•+以降低逆反應之情形。經由批次直接光解實驗,在pH 3,提供飽合溶氧或不特意供氧的條件下,結果皆得到產率大約70%的ABTS•+,因此本實驗採用後者條件應用於線上流動式光反應器進行線上直接光解產生ABTS•+,其產率也可達70%。CZE結合光氧化後衍生系統,可以簡單有效地分離五種混合樣品(L-ascorbic acid, D-isoascorbic acid, sorbic acid, benzoic acid, gallic acid)並同時偵測其抗氧化能力,電泳分離時間不超過18分鐘,其抗氧化能力分析的偵測極限約0.58 µM(進樣量~84 nL),經換算VCEAC值與文獻相符合。綜上所述,本研究建立之CZE-UV/ABTS系統具有快速、簡單且能夠線上即時產生ABTS•+試劑等優點,並已成功分析真實樣品之抗氧化能力。
Abstract 2, 2’-azinobis-(3-ethylbenzothiazoline-6- sulfonate acid) radical cation (ABTS•+) decolorization assay is one of the most widely used methods for analyzing the antioxidant capacity(AOC) in biological and environmental samples. A separation technique liquid chromatography combining with ABTS•+ post-column detection step has become a useful analysis approach. In this study, we present an on-line generated ABTS•+ as post-column with capillary electrophoresis for antioxidant capacity analysis. Ultraviolet (UV) irradiation at 254 nm was directly photolyed colorless ABTS to form blue-green colored ABTS•+. Furthermore, PTFE tubing coil was use to constitute a flow-through photoreactor as an on-line direct photolysis device. This system can simplify operating sequence and generate rapidly on-line ABTS•+ to reduce reverse reaction. Whether purging O2 or not, about 70% production of ABTS•+ was obtained individually both in batch and on-line direct photolysis experiments. Based on the on-line assay results, the CZE-UV/ABTS system has good precision and post-column signal was very stable at various pHs. The system can successfully separate five compounds and measure their antioxidant capacities simultaneously. The migration time was smaller than 18 min and detection limitedwas about 0.58 μM (injection sample: 84 nL). The antioxidant capacity value of compounds shows a good agreement with reported data. In conclusion, the CZE-UV/ABTS system is feasible to determine the antioxidant capacity of real samples.
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