Prediction of Plate Height Curves of Porous-Shell Pillar Array Columns Micro-Pillar Array Columns

Abstract

We investigate band broadening in the most widely adopted configuration of micro-pillar array columns (μPACs)—specifically, a cylindrical pillar array where both the pillar walls and the channel bottom are coated with a thin layer of mesoporous material. The two-zone moment analysis method is adopted to investigate the dispersion properties of μPACs in a broad range of shell thicknesses, reduced fluid velocities, and retention factors. Three different models of the unit cell, of increasing complexity, have been implemented, namely a two-dimensional model and two different three-dimensional models with and without the retentive bottom layer, the presence of which seems to have a very significant effect on the plate height curves. Model predictions are compared with experimental van Deemter curves for uncoated and coated porous layers, and a robust relationship between the intra-particle (porous-zone) diffusion coefficient Dpz and the retention factor k′ is established.

Keywords

• micro-liquid chromatography
• micro-pillar array columns
• band broadening
• dispersion theory
• plate height model
• finite element method (FEM)