Holographic refractive index detector for application in microchip-based separation systems

A novel detection scheme for capillary electrophoresis on planar glass microchips is presented. The application of a holographic-based refractive index detector to the electrophoretic separation of carbohydrates is described. The microchip device consists of a cyclic (square) separation channel having a circumference of 80 mm, a width of 40 µm and a depth of 10 µm. The volume of the injection scheme is approximately 16 pl. Separation and refractive index detection of a mixture of sucrose, N-acetylglucosamine and raffinose, each at a concentration of 33 mM, was achieved within 17 s of injection. Preliminary results demonstrate the feasibility of using hologram-based refractive index detectors in microchip separation systems. Although the initial detection limits are poor in comparison with alternative techniques, the potential of a universal detector of this kind is clear.