High surface area chromatographic device with low pressure drop

A chromatographic method, comprising:

• providing a chromatographic device comprising:
• a plurality of diffusive media elements spaced apart from each other a separation distance;
• a primary channel defined between the plurality of diffusive media elements having a cross-sectional area and characteristic length such that analyte travel within the primary channel is substantially convective;
• and
• a plurality of secondary channels located in each diffusive media element, each having a cross-sectional area and characteristic length such that analyte flow into and out of a secondary channel is substantially diffusive, each of the plurality of secondary channels having an entrance in fluidic communication with the primary channel wherein the entrance intersects the primary channel, wherein the secondary channels have a closed end;
• and
• introducing an analyte through each of the primary and secondary channels of the chromatographic device, wherein the Pećlet number for the analyte in the primary channel is between 1 and 10 and the Pećlet number for the analyte in each of the secondary channels is less than 0.2, wherein a diffusion coefficient of the analyte is between about 1×10−7 m2/s to about 1×10−12 m2/s.