OPTIMIZATION OF EXCITATION AND DETECTION GEOMETRY FOR MULTIPLEXED CAPILLARY ARRAY ELECTROPHORESIS OF DNA FRAGMENTS

A new on-column excitation and detection geometry for multiplexed array capillary electrophoresis is evaluated. The detection limit is improved 100-fold for the same laser power because of more efficient coupling of the laser beam. The illumination is also more uniform over the entire array. Stray light and cross-talk are effectively suppressed by immersing the capillaries in water to roughly match the refractive index. A charge-coupled-device (CCD) camera combined with cutoff filters provides adequate sensitivity and speed for high-speed DNA sequencing based on sieving in a polymer-matrix solution.