[Preparation and evaluation of monolithic silica columns for capillary electrochromatography]

A solution of methacryloxypropyltrimethoxysilane in the presence of an acid catalyst, water, toluene and azobisisobutyronitrile (AIBN) was initiated at 60 degrees C for 24 h in a 100 microm i.d. capillary to prepare a porous monolithic silica column by a one-step, in situ, process. Various parameters, such as the volume of applied voltage, buffer pH, acetonitrile concentration and column temperature, were varied to assess their influence on retention mechanism, electroosmotic flow (EOF) and column efficiencies. The heat initiated sol-gel capillary monolithic column showed reversed-phase behavior. Furthermore, the homogeneous reactor was obtained using surfactant (sodium dodecyl sulfate, SDS). The baseline separation of 9 neutral compounds (thiourea, benzene, toluene, ethyl benzene, n-propylbenzene, naphthalene, n-butylbenzene; fluorene and anthracene) and 7 acidic, basic and neutral compounds (thiourea, o-aminophenol, phenol, benzene, o-methylaniline, alpha-naphthylamine, 2,4-dichloroaniline) can be obtained under optimized capillary electrochromatographic conditions. Column efficiency of 110,000 plates/m was achieved for thiourea.