Extremely uniform packing of colloidal silica in capillaries is shown. Reversed-phase electrochromatograms of DiIC_(12) exhibit plate heights as low as 0.23 (mu)m and a reduced plate height as low as 0.7, using 75 (mu)m i.d. capillaries packed with 330 nm silica particles. The contribution from the A term is 0 +- 20 nm in electro-chromatography. The particles are shown to form colloidal crystals inside the capillaries. Optical images show Bragg diffraction, indicative of crystallinity. Scanning electron microscopy (SEM) images show face-centered cubic crystallinity, and the porosity is 0.25 +- 0.01, which is in agreement with that for face-centered cubic crystals. The capillaries are fritless, and 100 (mu)m i.d. capillaries packed with silica colloidal crystals withstand pressures of at least 12 400 psi.
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