Electroosmosis- and pressure-driven chromatography in chips using continuous beds

The application range of microchips can be extended to any mode of chromato graphy by filling the narrow channels with continuous polymer beds, exempli fied by electrochromatography and ion-exchange chromatography. "Wall effect s" are eliminated by anchoring the bed to the wall of the channel, an arran gement which has the additional advantage that no hits to support the bed a re required. The design of the equipment is based on a quartz chip with all auxiliary pieces (for example, electrode vessels and fluid transfer fittin gs) placed in a rack, which permits a flexibility of great importance for a utomation. The same resolution and van Deemter plots were obtained in exper iments performed in fused-silica capillaries and in chips for both low-mole cular-weight (alkyl phenones, antidepressants) and high-molecular-weight su bstances (proteins). A sample of uracil, phenol, and benzyl alcohol was sep arated by electrochromatography in less than 20 s.