Recent developments in the field of monolithic stationary phases for capillary electrochromatography

This review summarizes the contributions to the rapidly growing area of monolithic columns based on both silica and synthetic polymers for capillary electrochromatography and chip electrochromatography, with a focus on those published during the year 2004. A wide variety of both modified approaches to the "old" monoliths and new monoliths have been reported despite the very short period of time covered. This demonstrates that monolithic stationary phases have become a well-established format in the field of electrochromatography. The simplicity of their preparation as well as the good control over their porous properties and surface chemistries make the monolithic separation media an attractive alternative to capillary columns packed with particulate materials.

Capillary electrochromatography column behavior of butyl and lauryl acrylate porous polymer monoliths

A variety of porous polymer monoliths (PPMs) have been synthesized using the 'conduct-as-cast' format. The resulting polymers have been evaluated for use as separation media in capillary electrochromatography (CEC). The results have shown that substituting a small percentage of the standard polymer formulation with a more hydrophobic monomer produced columns with expected increases in retention for a neutral analyte series. However, substituting larger percentages of a more hydrophobic monomer resulted in columns that exhibited less retention. The unexpected behavior of these hydrophobic columns has been attributed to the non-uniform polymeization of the moree hydrophobic monoliths. Van Deemter plots of polyaromatic hydrocarbons have been examined to further analyze the unexpected behavior of these columns. Hmin values ranged from 8.7 to 9.1 microm for the columns evaluated. The effect of the percentage of organic modfier in the phase on the separation has also been studied. The retention window decreases when altering the ACN concentration in the mobile phase from 50% to 80% (v/v).