These experiments show that the bead bed(s) facilitate formation of both an IDZ that fills the channel cross section and small fluid vortices that support overlimiting current without disruption of analyte focusing. Next, we observed that the rate of enrichment of a small molecule fluorophore is greater in both bead bed designs but more dramatically for the PSC/Ag/Au -a result, which is attributed to the higher electric field strength and fluid velocity within the resistive PSC bead bed.