Preparation and Characterization of Monolithic Porous Capillary Columns Loaded with Chromatographic Particles

Abstract

Using sol-gel technology, a porous glass matrix (xerogel) is formed in a capillary column and acts as a support for a stationary phase of chromatographic particles used in capillary electrochromatography. Preparation of the sol-gel matrix and immobilization of the octadecylsilica (ODS) stationary phase occur in a single step. The presence of the particles in the column greatly reduces matrix cracking caused by internal pressure differentials within the pores of the sol-gel matrix. Good electroosmotic flow 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. Efficiencies of up to 80 000 plates/m were observed in columns with immobilized 3-μm ODS particles. The efficiency and resolution are enhanced when 3-μm ODS particles are used in place of the 5-μm particles.

Hybrid organic-inorganic phenyl monolithic column for capillary electrochromatography

“…Up till now, both organic polymer [3][4][5] and silica-based [6][7][8][9][10] monoliths have been developed. Polymeric monolithic stationary phases have the advantage of simple polymerization procedure and easy tuning of porosity and surface chemistry, but they suffer from shrinking or swelling when exposed to different organic mobile phases, leading to lack of mechanical stability.…”

“…Polymeric monolithic stationary phases have the advantage of simple polymerization procedure and easy tuning of porosity and surface chemistry, but they suffer from shrinking or swelling when exposed to different organic mobile phases, leading to lack of mechanical stability. Monolithic silica capillary columns can be prepared by sintering silica particles [6], immobilizing silica particles in a silica xerogel matrix [7], or in situ hydrolytic polycondensation of alkoxysilanes by a sol-gel process [8][9][10]. The latter one is the most widely used.…”

Capillary Electrochromatography on Monolithic Silica Columns

“…A continuous-bed structure can be formed starting from a packed bed of silica particles in a capillary by bonding the particles together. [3][4][5][6][7] Such monolithic silica columns (20 -25 cm long) provided 40000 -70000 theoretical plates that were somewhat fewer than that of a column packed with particles without such a treatment. Monolithic columns based on organic polymers have been prepared from monomers in a capillary.…”

A new method for reconstruction of the structure of micro-packed beds of spherical particles from desktop X-ray microtomography images. Part A. Initial structure generation and porosity determination

“…A number of workers have used scanning electron microscopy (Liang et al, 2003, Motokawa et al, 2002, Dulay et al, 1998 and transmission electron microscopy (Courtois et al, 2006, Plummer et al, 1995. These techniques are, however, tedious to extend to quantitative characterization of the three-dimensional (3D) structure of µPBs.…”