Numerical Method for the Estimation of Column Radial Heterogeneity and of the Actual Column Efficiency from Tailing Peak Profiles

Abstract

It is probably impossible to prepare high-performance liquid chromatography (HPLC) columns that have a completely homogeneous packing structure. Many reports in the literature show that the radial distributions of the mobile phase flow velocity and the local column efficiency are not flat, even in columns considered as good. A degree of radial heterogeneity seems to be a common property of all HPLC columns and an important source of peak tailing, which prevents the derivation of accurate information on chromatographic behavior from a straightforward analysis of elution peak profiles. This work reports on a numerical method developed to derive from recorded peak profiles the column efficiency at the column center, the degree of column radial heterogeneity, and the polynomial function that best represents the radial distributions of the flow velocity and the column efficiency. This numerical method was applied to two concrete examples of tailing peak profiles previously described. It was demonstrated that this numerical method is effective to estimate important parameters characterizing the radial heterogeneity of chromatographic columns.

Determination of the Exact Particle Radius Distribution for Silica Nanoparticles via Capillary Electrophoresis and Modeling the Electrophoretic Mobility with a Modified Analytic Approximation

“…It is known that the determination of κ 3 and κ 4 by a moment analysis requires a high signal-to-noise-ratio. 79 Improvement of precision and accuracy of the developed method requires an improvement of the signal-to-noise-ratio of the recorded electropherograms. To this end, coupling of CE with a more sensitive detection method is highly desirable.…”

“…The parameter κ 4 , however, which characterizes the excess of a distribution, was determined with very high inaccuracy. It is known that the determination of κ 3 and κ 4 by a moment analysis requires a high signal-to-noise-ratio …”

Mechanistic modeling of cation exchange chromatography scale‐up considering packing inhomogeneities

“…This effect could explain the varying peak shape, which was compensated in the first empirical approach with a shielding factor variation at different column scales. In the literature, various publications can be found which investigate the influence of inhomogeneous column packing in the linear and non-linear range [15][16][17][18][19][20][21][22][23][24][25][26]. It is shown that packing inhomogeneities in the radial direction of the column lead to different radial velocity profiles, which can significantly influence the peak shape in low and high-loading conditions [17].…”

“…Furthermore, packing inhomogeneities within a column result in a radial packing density profile, which in turn results in a radial velocity profile that may significantly affect the elution profile of the target molecule. Several publications have shown that radial packing inhomogeneities can strongly influence the peak shape in the linear and non-linear range [15][16][17][18][19][20][21][22][23][24][25][26]. Considering all these influences in a mechanistic model across different column scales is challenging.…”

A study of mass transfer kinetics of alanyl-alanine on a chiral crown ether stationary phase

“…Unsymmetrical peaks, when linear conditions are proven, reveal slow mass transfer. A large tailing may indicate either slow desorption kinetics [5,38,39] or the irregularity of the packing structure across the column [49]. The shape of the peaks of Ala-Ala evolves from a quite symmetrical, close to Gaussian one at high flow velocities to unsymmetrical with a pronounce tail at low flow velocities (Fig.…”