Description of the Retention and Peak Profile for Chromolith Columns in Isocratic and Gradient Elution Using Mobile Phase Composition and Flow Rate as Factors

Abstract

Abstract:The effect of the modifier concentration and flow rate on the chromatographic performance of a second generation Chromolith® RP-18e column, under isocratic and gradient elution with acetonitrile-water mixtures, was examined using four sulphonamides as probe compounds. The acetonitrile concentration was varied between 5 and 55% (v/v), and the flow rate between 0.1 and 5.0 mL/min, keeping the other factors constant. The changes in both retention and peak profile were modelled, and used to build simple plots, where the logarithm of the retention factor was represented against the modifier concentration (in gradient elution, against the initial modifier concentration), and the half-widths or widths against the retention time (in gradient elution, against the time at the column outlet). A particular plot was needed for describing the retention of each sulphonamide, but due to the similar interaction kinetics, a unique plot described the changes in the half-widths for all four sulphonamides. The changes in retention with the flow showed that allegedly in the second generation Chromolith, the column deformation observed for the first generation Chromolith, with the applied pressure at increasing flow, is decreased.

Reversed‐phase ion‐pair chromatography‐diode array detection of the bispyridinium compound MB327: plasma analysis of a potential novel antidote for the treatment of organophosphorus poisoning

“…Such a profile is explained by the flow‐dependent impact of three different transport processes determining peak broadening (described by W 0.5 ) and thereby chromatographic efficiency. Eqn (11) (Table ) reflects this relation considering Eddy diffusion (A term), longitudinal diffusion (B term) and the resistance to mass transfer of the analyte between mobile and stationary phase (C term) . For more details the reader is referred to common textbooks on chromatography.…”

“…Systematic analysis of temperature‐dependent retention times (t R ) allows to generate a van´t Hoff plot characterizing thermodynamic properties of the analyte transfer between stationary and mobile phase . Monitoring flow‐dependent retention time shifts are used to generate a van Deemter plot that characterizes diverse processes of analyte diffusion and transfer between both phases that affect peak shape and therefore chromatographic efficiency . Evaluation of such data is of fundamental interest especially for RPIPC as retention mechanisms are still not understood completely .…”

Sub-2 μm Silica Particles in Chiral Separation

“…Instead, tuning the column length together with the stationary phase morphology (e.g. particle size) can result in a better compromise between the plate count and analysis time [36,37]. Column length and plate count are related through the height equivalent to one theoretical plate with the relationship between the theoretical plate and mobile phase velocity described by VDE as the sum of different band-broadening contributions [34][35][36].…”

Prediction of Peak Shape and Characterization of Column Performance in Liquid Chromatography as a Function of Flow Rate

“…Even in these cases, Equation (3) is applied, using numerical integration to obtain the retention times and variances. For non-Gaussian peaks, the representation of the left and right half-widths at fixed flow rate instead of the variance, versus the retention time, offers additional information about the peak profiles [7,[16][17][18]. Although the plots are slightly parabolic inside large retention time ranges, they are linear within practical ranges: Equations (4) to (6) have been demonstrated to be useful to predict peak profiles with optimization purposes, to characterize chromatographic columns and to reveal the interaction kinetics of solutes [17].…”

“…When the solutes experience different kinetics, the model parameters will be solute dependent and should be obtained for each solute using mobile phases of variable composition (in order to obtain data at different retention times). Recently, the half-width (width) plots approach has been adapted to gradient elution [18,19].…”