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Capillary gel electrophoresis is demonstrated for the four-spectral-channel sequencing technique of Smith, the two-spectral-channel sequencing technique of Prober, and the one-spectral-channel sequencing technique of Richardson and Tabor. Sequencing rates up to 1000 bases/h are obtained at electric field strengths of 465 V/cm. At lower electric field strengths, capillary electrophoresis produces useful data for fragments greater than 550 nucleotides in length with 2 times better resolution than slab gel electrophoresis. An on-column detector produces detection limits of 200 zmol (1 zmol = 10(-21) mol = 600 molecules) for the four-spectral-channel technique. A postcolumn detector, based on the sheath flow cuvette, produces detection limits of 20 and 2 zmol for the two- and one-spectral-channel techniques, respectively.

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In a capillary zone electrophoresls system wlth a sheath flow detector, the preosurlzed detector induces a component of flow oppodte to that of electrophoresls. This pressure-induced flow, because of Its nonunlform velocity profile, can degrade the separatkn. However, theory predlcts and experlmenl vertlbs that, under normal operating condltlons, the detector does not degrade the separation. The major source of band broadenlng at pH 9 and 10 is due to longltudlnal diffusion, although In/ectlon volume can lhnlt the perlormance of the system. When Injection volume Is minlmlzed, over 2.5 million theoretical plates are obtained for the analysis of fluorescein thlocarbamyi derlvatives of amino acids in a 10-min separatlon. A b , dlffuslon coefficients and electrophoretic mobilitles may be measured wlth good accuracy. The low flow rate of capillary zone electrophoresis affects the performance of the sheath flow cuvette. Theory predicts and experiment verlfles that the peak helght In capillary zone electrophoresls wlth the sheath flow detector increases ilnearly with separation voltage. A model is also presented for the sample stream r a d b expected in the sheath flow cuvette for analytes that undergo radial diffusion.Capillary zone electrophoresis is a particularly powerful technique for the analysis of ions (1-10). In the technique, separation is based on differential migration of analyte in a buffer-filled capillary under the influence of an electric field.Because the number of theoretical plates produced during the separation is proportional to the applied voltage, very efficient separations may be produced by very high potentials. In this laboratory, theoretical plate counts greater than lo6 are routinely produced with separation potentials of 30 kV.