Free-zone electrophoresis in glass capillaries

A simple theory of zone electrophoresis in open-tubular capillaries is developed. According to this theory, to achieve the highest resolution of zones, tubes with as small an inside diameter as possible should be used in combination with as high an applied voltage as feasible. To test this approach, we performed electrophoresis in glass capillaries with an internal diameter of 75 micron and a length of 100 cm. A special fluorescence detector was used to detect fluorescent zones while they migrated inside the capillary. With the application of 30 kV potentials to this system, rapid and efficient separations of amino acids, peptides, and urinary amines were demonstrated. In all cases fluorescent derivatives were necessary for detection. Preliminary results are encouraging, and with further development of sensitive detection devices, applications in clinical analyses may be feasible.