Comparison of rate models for gradient elution chromatography and experimental evaluation for IEC, HIC, and RPC...

Area of Science:

• Chromatography
• Chemical Engineering
• Analytical Chemistry

Background:

• Solvent gradients are crucial in elution chromatography for optimizing separations.
• Accurate modeling of chromatographic processes under gradient conditions is essential for method development.

Purpose of the Study:

• To evaluate the performance of four rate models (pore diffusion, linear driving force, and two transport models) in describing solvent gradient elution.
• To develop an analytical solution for gradient elution chromatography and compare it with numerical solutions.

Main Methods:

• Comparison of pore diffusion (PD), linear driving force (LDF), and two transport models (TRQ, TRC) against experimental data.
• Development of a new analytical solution for the TRC model applicable to arbitrary gradient shapes.
• Analysis of peak sharpening and peak shape under varying gradient steepness.

Main Results:

• All four models accurately predict peak sharpening for shallow gradients.
• Transport models show deviations for steep gradients.
• PD, LDF, and TRC models predict fronting peak shapes with strong initial adsorption, consistent with experimental observations.

Conclusions:

• The TRC model offers a practical balance of simplicity and accuracy for solvent gradient calculations in chromatography.
• The developed analytical solution for the TRC model facilitates easier application in various chromatographic systems.