Laser-induced fluorescence detector with a fiber-coupled micro GRIN lens for capillary electrophoresis

Capillary electrophoresis coupled with sheath-flow laser-induced fluorescence (LIF) detection has been shown to offer outstanding sensitivity for chemical and biochemical analysis. However, a major drawback remains with the complexity of the optical configuration traditionally employed. Here we present a simplified confocal optics based on fiber optics and micro gradient-index (GRIN) lenses for modular optical design in capillary electrophoresis with laser-induced fluorescence. We demonstrate the use of the optical system with a sheath-flow cuvette as the laser-induced fluorescence detector for capillary electrophoresis. The system's performance was established with concentration detection limits of 8±2pM and mass detection limits of 57 zeptomole for a standard sodium fluorescein sample.