毛細管微胞電泳層析掃集濃縮法結合77 K低溫螢光光譜分析對紅葡萄酒中微量逆轉醇即時光譜的鑑定與研究

Abstract

本研究完成首次結合線上濃縮和毛細管電泳層析低溫螢光光譜偵 測法，並同時確認紅葡萄酒中逆轉醇77 K低溫的光譜。 利用sweeping-MEKC毛細管電泳層析法進行線上濃縮並分離逆轉 醇，當逆轉醇到達偵測窗口，瞬時將溫度降至77 K，測量on-line螢光光 譜，並和標準品的77 K低溫螢光光譜作指紋比對。 偵測紅酒萃取物中的逆轉醇最佳分離條件為matrix 20 mM H3PO4，分離緩衝溶液內含30 mM H3PO4、150 mM SDS，溶液中甲醇 和水的比例為25:75 (v/v)。和normal-MEKC毛細管電泳層析法相比較， 使用sweeping-MEKC的毛細管電泳層析法，可以在偵測靈敏度上增加 1500倍。最低偵測極限是5 ppb (S/N = 3)，偵測條件為激發螢光波長313 ± 8 nm，吸收螢光波長400 ± 16 nm，使用濾光片濾掉320 nm以下的光 線。 利用毛細管微胞電泳層析濃縮掃集，結合on-line 77 K 螢光光譜偵 測法，不只可在紅酒萃取物中分離並偵測逆轉醇，且77 K低溫的線上 螢光光譜，更可確認逆轉醇在紅葡萄酒中的真實存在。

The feasibility of combining the techniques of on-line concentration and capillary electrophoresis/low temperature fluorescence spectroscopy (CE/LTFS) in the detection and identification of trans-resveratrol in red wine at 77 K is demonstrated for the first time. This technique, involving sweeping-micellar electrokinetic chromatog -raphy (sweeping-MEKC), was used for the initial on-line concentration and separation, after which, a cryogenic molecular fluorescence experiment was performed at 77 K. The complete, optimal separation of trans-resveratrol from a red wine extract (in a sample matrix (an aqueous 20 mM H3PO4 solution)) could be achieved with phosphate buffer(30 mM) containing SDS (150 mM) in a methanol -water solution (25:75 v/v) , and a 1500-fold improvement in detection sensitivity was obtained compared with the normal-MEKC method. The limit of detection is 5 ppb (LOD). (S/N = 3). The excitation wavelength was 313 ± 8 nm; the emission was measured at 400 ± 16 nm(with 320 nm cut filter). The proposed method permits, not only the separation and detection of trans-resveratrol from red wine extracts, but also ensures that the on-line spectrum is readily distinguishable and can be un-ambiguously assigned at 77 K.