Anal. Chem. 2002, 74, 639-647
An Integrated Fritless Column for On-Chip Capillary Electrochromatography with Conventional Stationary Phases Laura Ceriotti,* Nico F. de Rooij, and Elisabeth Verpoorte
SAMLAB, Institute of Microtechnology, University of Neuchaˆ tel, Neuchaˆ tel, Switzerland
A new polymer device for use with conventional particulate stationary phases for on-chip, fritless, capillary electrochromatography (CEC) has been realized. The structure includes an injector and a tapered column in which the particles of the stationary phase are retained and stabilized. The chips were easily fabricated in poly(dimethylsiloxane) using deep-reactive-ion-etched silicon masters, and tested using a capillary electrophoretic separation of FITC-labeled amino acids. To perform CEC, the separation channel was packed using a vacuum with 3-µm, octadecylsilanized silica microspheres. The packing was stabilized in the column by a thermal treatment, and its stability and quality were evaluated using in-column indirect fluorescence detection. The effects of voltage on electro-osmotic flow and on efficiency were investigated, and the separation of two neutral compounds was achieved in less than 15 s. The use of microfabricated fluidic substrates has become increasingly well-established for liquid-phase analysis in recent years. This is particularly true for electrokinetically driven separations, where etched microchannels provide an easy route to reduced column diameters and, hence, increased efficiencies and decreased solvent/sample consumption.1 As with narrow bore (
