Continuous Electrophoretic Separations in Narrow Channels Coupled to Small-Bore Capillaries

Continuous zone electrophoretic separations in channels have been demonstrated. This new technique has the potential to continuously sample and separate analytes from volume-limited microenvironments. A small-bore capillary is used to electrophoretically sample, but not separate, a mixture of dansylated amino acids. The capillary is coupled to a quartz channel structure in a manner which allows continuous injection of the sampled material into the channel. The channel functions to continuously separate the sampled material via electrophoresis. A laser-induced fluorescence detection scheme, which involves two fiber optic arrays situated at the channel exit, monitors eluting analytes. A continuous separation of dansylated amino acids on the time scale of a few minutes demonstrates the utility of the technique. Sampling has been performed continuously up to 400 s, and initial detection limits are ~30 µM.