Fabrication of monolithic frits and columns for chip-based multidimensional separation devices

In this work, devices for two-dimensional separations are considered. The device contains a flow distributor, a first-dimension channel, and 17 second-dimension outlets. In the design, all connections between the first-dimension channel, the flow distributor, and the second-dimension outlets were tapered, with a minimal diameter of 20 mu m. The use of photo-masking is explored for the fabrication of monolithic frits in all tapered connections. Monolithic frits with optimized permeability and length were successfully fabricated in all 33 tapered channels through light-induced polymerization, photo-masking, and selective exposure. The efficacy of the monolithic frits was demonstrated by creating a packed bed of 15-mu m particles, confined within the first-dimension channel. The outlet of the first-dimension channel was successfully connected to a mass spectrometer. Effective flow confinement was demonstrated with a reversed-phase separation of a mixture of five standard peptides.