Synthesis and Characterization of High-Affinity, Low-Molecular-Mass Displacers for Anion-Exchange Chromatography

In this paper, the synthesis and characterization of various low-molecular-mass anion-exchange displacers is described. A homologous series of displacers based on either triazine or phloroglucinol were synthesized. The displacer molecules were then characterized using the steric mass action (SMA) isotherm model and dynamic affinity lines resulting from this model. In addition to the dynamic affinity analysis, log P descriptors were calculated as well as several other molecular descriptors to characterize these molecules. The displacers were used to screen for their behavior on agarose-based Q Sepharose HP, hydrophilized poly(styrene−divinylbenzene)- (PS−DVB-) based Source 15Q, and poly(methyl methacrylate)-based ToyoPearl Super Q-650S stationary-phase materials. This work demonstrates that aromaticity/hydrophobicity is very important in increasing the affinity of displacers for anion-exchange resins regardless of their backbone chemistry. The results also indicate that a benzene ring is superior to a triazine ring in increasing the affinity of these anionic displacers. In addition, the data indicate that the location of an aromatic ring in the core enables the molecule to approach the stationary phase in a flat geometry, thereby increasing the number of charges interacting with the stationary phase. Finally, the results of a dynamic affinity analysis and displacement experiment confirm that this class of displacers can be readily used for protein purification by anion-exchange displacement chromatography.