Characteristics of particle-loaded monolithic sol–gel columns for capillary electrochromatography: I. Structural, electrical and band-broadening properties

Particle-loaded (3 μm, C18) monolithic sol–gel columns have been prepared and selected characteristics measured. They have a surprisingly high permeability, allowing their operation in the microLC mode at pressures as low as 69 kPa where their efficiency is about 50 000 plates per meter and the CEC mode where efficiency is at least 106 000 plates per meter. These columns can withstand over 13.8 MPa pressure without compression or movement within the 75 μm capillary. Field strengths in the packed segments are approximately 50% greater than those in the open segments, due to the higher resistivity of the particle-laden regions. There is a relatively rapid loss of efficiency with increasing linear velocity in both the CEC and microLC modes, which may be due to a tortuosity effect in the inter- and intra-particulate voids. Chromatographic behavior is characteristic of conventional C18 particles, indicating that analytes have significant access to the surface within the pores of the immobilized bonded phase.