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 refra ctive index detector to the electrophoretic separation of carbohydrate s is described. The microchip device consists of a cyclic (square) sep aration channel having a circumference of 80 mm, a width of 40 mu m an d a depth of 10 mu m. The volume of the injection scheme is approximat ely 16 pl. Separation and refractive index detection of a mixture of s ucrose, N-acetylglucosamine and raffinose, each at a concentration of 33 mM, was achieved within 17 s of injection. Preliminary results demo nstrate the feasibility of using hologram-based refractive index detec tors in microchip separation systems. Although the initial detection l imits are poor in comparison with alternative techniques, the potentia l of a universal detector of this kind is clear.