title: Detailed kinetic performance analysis of micromachined radially elongated pillar array columns for liquid chromatography.
abstract: The individual factors that determine the kinetic performance (B- and C-term band broadening and bed permeability Kv) of radially elongated pillar (REP) columns are studied. To this end, columns with REPs having 4 different aspect ratios (AR=9, 12, 15, 20) were characterized experimentally and by means of numerical simulations. A tortuosity and retention based plate height equation was established, enabling a good global fit for all studied conditions. The B-term plate height contribution appears to decrease with a factor equaling the square of the flow path tortuosity τ. Going from AR=12 to AR=20 (τ=5.7 and τ=9.0 respectively), this resulted in a shift in plate height expressed in axial coordinates from Hmin=0.42 μm to Hmin=0.25 for non-retained conditions and from H=0.77 μm to H=0.57 μm for a component with k=1.0. The obtained parameters were combined to predict optimal time-efficiency combinations for all possible channel lengths. This revealed an efficiency limit of N=10(7) plates for a non-retained component and N=7-8 × 10(6) for k=1 for a channel with an AR=20, corresponding to a channel length of 2.5m and a void time of 2.4h.
authors.affiliation: Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; B-PHOT, Department of Applied Physics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Manly
authors.initials: M
authors.lastname: Callewaert
authors.affiliation: Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: Desmet
authors.affiliation: B-PHOT, Department of Applied Physics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Heidi
authors.initials: H
authors.lastname: Ottevaere
authors.affiliation: Department of Chemical Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium. Electronic address: wdemalsc@vub.ac.be.
authors.forename: Wim
authors.initials: W
authors.lastname: De Malsche
mesh_terms: D002853:Chromatography, Liquid / Q000295:instrumentation*; D003374:Coumarins / Q000032:analysis; D004058:Diffusion; D007700:Kinetics; D056656:Lab-On-A-Chip Devices; D010539:Permeability
chemical_list: D003374:Coumarins; C028743:7-amino-4-methylcoumarin
keywords: Column packing; Lab-on-a-chip; Microfluidics; Open tubular; Pillar array column; Radially elongated pillar