Post-capillary laser-induced fluorescence detection without sheath-flow

The sensitivity of laser-induced fluorescence detection in capillary electrophoresis is generally limited by noise due to scattering of the excitation beam on the capillary walls. The highest sensitivities have been obtained with post-capillary detection in a sheath-flow cuvette. In this paper, we report a new method for post-capillary detection, avoiding the hydrodynamic buffer flow at the capillary outlet. In our detection scheme, the analytes coming out of the individual capillaries are kept well separated from their neighbours in the outlet detection chamber because of an adequate electric field surrounding the capillary extremities.