Development of a capillary electrophoresis-77 K luminescence detection system for online spectral identification.

We have demonstrated that capillary electrophoresis (CE) can be easily interfaced with 77 K luminescence spectroscopy (LS) for separation and online spectral identification of structurally similar analytes. This novel CE-LS apparatus consists of a regular CE system, instrumentation for LS and a specially designed capillary Dewar. When the separating molecules traverse into the cryostat detection window, liquid nitrogen is added, freezing the separating analyte zones within the capillary. At low temperature, detection limits are improved via signal averaging and the inherent increase in quantum yield at 77 K. We present the first application of the CE-LS system to structural isomers (2,3- and 3,4-methylenedioxymethamphetamine) and stereoisomers (trans- and cis-resveratrol). With this approach, the CE-LS interfacing provides a sensitive, accurate, rapid, simple and economic methodology for analytical chemistry.