title: Interpreting the difference between conventional and bi-directional plate-height measurements in liquid chromatography.
abstract: An experimental and theoretical study was conducted of the column characterization technique in which plate heights determined using the conventional pulse-response method are compared with those determined using a bi-directional method where an eluite sample is introduced into one end of a chromatographic column and elution occurs at the same end after the flow direction is reversed inside the column. Experiments are presented for a micropellicular HPLC column before and after its performance has been degraded by repeated sample injections, for a low-pressure column containing nonporous glass particles, and for an HPLC column containing particles with 300 A pores. The results obtained are interpreted in terms of several different theories which apply in various Fourier number ranges. It was shown that the transcolumn contribution to convective dispersion in a chromatographic column is largely responsible for the difference observed between conventional and bi-directional plate-height measurements and that a collocation method can be employed to develop a useful analytical expression for this contribution.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Guo
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Frey
mesh_terms: D000465:Algorithms; D002853:Chromatography, Liquid / Q000379:methods*; D005898:Glass; D008962:Models, Theoretical; D010316:Particle Size; D016062:Porosity; D012212:Rheology / Q000379:methods*