Modeling the cAMP desorption process from an anion exchange chromatography column

Computational modeling is a useful approach for the characterization, development, and validation of desorption chromatography. Batch and dynamic desorption experimental results are helpful for the selection of an appropriate desorbent and the design of a desorption processes. In this study, we used an aqueous HCl solution ranging from 0.030mol/L to 0.060mol/L to desorb cAMP (adenosine 3',5'-cyclic monophosphate) from a presaturated anion exchange resin (D-13). Good results were obtained in terms of the desorption rate and cAMP recovery. Subsequently, general rate model (GRM) that incorporated counter-ion flux was used to describe the desorption kinetics of the batch experiments. The superficial rate constant, K _d, of the cAMP/HCl reaction on activated ion exchange sites inside the resin was estimated as 0.130L/(mol/s) using the least squares fitting method, which was then applied for predicting the dynamic desorption processes. The pore diffusion coefficients for Cl ^- and cAMP were estimated as 1.57×10 ^-9 and 5.71×10 ^-10m ²/s, respectively. We verified the applicability of this GRM model to a column desorption process by experimentally investigating the effects of the HCl concentration, flow rate, and column aspect ratio on column desorption. The experimental results could be predicted successfully using the GRM model. The validated GRM may provide an important basis for future scale-up of the cAMP desorption process.