The advantages and disadvantages of packed capillary columns for high performance liquid chromatography are examined. Historically, the advantages are smaller sample and phase consumption, enhancement in sensitivity, easy column synthesis, higher obtainable efficiency, and easier interfacing to other techniques. These points are explored through experiments in microbore ion chromatography, packed fused silica columns, and capillary zone electrophoresis. These studies also address the disadvantages of microscale HPLC which are stringent instrument design, brittle or weak columns, poor column stability, and the lack of commercial instrumentation. The results of these investigations indicate the following. First, the purported sensitivity enhancement is really attributable to solute focusing and not to column miniaturization. Second, column synthesis is still a difficult procedure that requires experience. Third, higher efficiencies are realized, especially when the column diameter to particle diameter ratio is optimized. Fourth, interfacing to other techniques is simplified because of the lower volumetric flow rates. Finally, the only real disadvantages are stringent instrument design and brittle columns in some instances. This thesis offers means for circumventing these difficulties. / Ph. D.