Preparation and characterization of monolithic porous capillary columns loaded with chromatographic particles

Using sol-gel technology, a porous glass matrix (xerogel) is formed in a ca pillary column and acts as a support for a stationary phase of chromatograp hic particles used in capillary electrochromatography. Preparation of the s ol-gel matrix and immobilization of the octadecylsilica (ODS) stationary ph ase occur in a single step. The presence of the particles in the column gre atly reduces matrix cracking caused by internal pressure differentials with in the pores of the sol-gel matrix. Good electroosmotic now is achieved in part because of the inherent negative charge of both the particles and the sol-gel matrix. The performance of these sol-gel/ODS capillary columns was evaluated with a mixture of aromatic and nonaromatic organic compounds. Eff iciencies of up to 80 000 plates/m were observed in columns with immobilize d 3-mu m ODS particles. The efficiency and resolution are enhanced when 3-m u m ODS particles are used in place of the 5-mu m particles.