Protein Mass Transfer Kinetics in Ion Exchange Media: Measurements and Interpretations

Abstract

The paper gives a summary of successful methods for measuring protein mass transfer kinetics in ion exchange matrices along with models needed to interpret experimental results. Both macroscopic methods (isocratic elution, gradient elution, batch adsorption, frontal analysis) and microscopic methods are considered. In all cases the main focus is the determination of the effective intraparticle diffusivity in order to permit a comparison of different stationary phases and provide a basis for predicting chromatographic process performance. Experimental results for representative systems are evaluated alongside the experimental and modeling aspects. Practical criteria for the selection of experimental conditions and the application of different models are discussed along with the advantages and disadvantages of the various approaches.

Impact of denaturation with urea on recombinant apolipoprotein A‐IMilano ion‐exchange adsorption: Equilibrium uptake behavior and protein mass transfer kinetics

“…4 were fit to a macropore diffusion model. This is of interest as mass transfer resistance is typically the principal cause of band broadening for the preparative ion-exchange chromatography of proteins [25]. The following equations provide a description of fixed-bed adsorption incorporating external film resistance, axial dispersion, and diffusion in large open pores within the particle [38]:…”

“…However, an analytical solution exists in the irreversible limit, which is satisfied for a Langmuir isotherm when [41]: (8) where R is the separation factor and C ref is a reference concentration. The feed concentration C F is normally the reference concentration [25]. When the criterion in Eq.…”

“…As the saturation capacity is approached, the experimental results for all urea concentrations "tail" and diverge slightly from the model. A number of theories have been advanced to explain this phenomenon, which is a common feature of protein breakthrough curves on ion exchangers [25,44,45]. Perhaps most interestingly, the fitted effective diffusivity value obtained in the absence of urea D e =4.5 × 10 -9 cm 2 /s was more than an order of magnitude lower than that obtained when the protein was fully denatured with 6 M urea, D e =6.0 × 10 -8 cm 2 /s.…”

“…For bioprocess applications where large diameter adsorbent beads and high mobile phase velocities are typically utilized, chromatographic efficiency is nearly completely determined by mass transfer kinetics [25]. Accordingly, numerous studies have been devoted to protein mass transfer in chromatography media (e.g., [26][27][28][29][30][31]).…”

Protein Adsorption in Tentacle-Type Anion Exchangers and the Influence of Process Related Fouling

“…A Cole-Parmer peristaltic pump recirculated the solution though a UV detector at 280nm (GE Healthcare, Model UV1) in order to determine the protein concentration as a function of time (Carta et al, 2005). A stainless steel 5-µm pore filter was used to prevent resin particles from entering the UV detector.…”