Development of a 1.0 mm inside diameter temperature-assisted focusing precolumn for use with 2.1 mm inside diameter columns

Experimental van Deemter curves indicate that the reduced velocity in the precolumn at 250 μL/min flow rate is about 50. Nonetheless, about 1000 theoretical plates are generated. When operating as a precolumn, clear advantages are seen for solutes across a range of modest k' values (2.2-23.4 at the separation conditions at 65 °C) using TASF alone (5 °C) with 50 μL injection volumes of methyl through n-butyl parabens, and with 100 μL injections that also include solvent-based focusing (90:10 aqueous/acetonitrile sample, 80:20 mobile phase).