Sol-Gel Stationary Phases

Sol-gel is basically a synthetic glass with ceramiclike properties. The processing consists of hydrolysis and condensation of a metal alkoxide (i.e., tetraethoxysilane) to form a glassy material at room temperature. Further modification of this material with a polymer (stationary phase) is used to prepare phases for capillary columns there has been keen interest in this process (118-123). The final sol-gel product retains the properties of the polymer as well as the properties of the sol-gel component. The sol-gel material is able to covalently bond to fused silica. 

Illustration showing the anchoring of the soLGEL material (naprsssnted hers as spheres) to the surface of the fuaed silica. 

Conventional Wax-type column with the phase coated onto the surface of the fused silica — no anchoring. 

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Another way to control the EOF is to vary the composition of the surface-bonded sol-gel stationary phase [60]. A sol-gel ODS-coated column was prepared with significantly stronger EOF mobility than the uncoated column. It was found that the magnitude of EOF increases (shifts toward more negative values) when the percentage of organic modifier in the mobile phase was increased. 

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