On-line identification of trans-resveratrol in red wine using a sweeping technique combined with capillary electrophoresis/77 K fluorescence spectroscopy.

The feasibility of combining the techniques of on-line concentration and capillary electrophoresis/low-temperature fluorescence spectroscopy (CE/LTFS) for 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 chromatography (sweeping-MEKC), was used for the initial on-line concentration and separation, after which a cryogenic molecular fluorescence experiment was performed at 77 K. In comparison with normal-MEKC mode, a approximately 1500-fold improvement in detection sensitivity could be obtained when the sweeping-MEKC was applied. 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 unambiguously assigned at 77 K.