A method for suppressing pH excursion during elution in ion-exchange chromatography

• Suppression of pH excursion during elution in cation exchange chromatography. • Simple method involving anion exchange cartridge in series during elution. • Hypothesis of working principle of the above. • Decrease in width of eluted peak. • Potentially greater control on separation and enhanced stability of eluted species. A simple method for reducing pH excursion during salt-induced elution in cation exchange chromatography is presented in this paper. Connecting a preequilibrated anion exchange cartridge in series in front of the cation exchange device just prior to the elution step significantly reduced the transient decrease in pH that is typically observed during elution. The working principle of the proposed method is hypothesized. Bind and elute chromatography experiments showed that the suppression of pH excursion during elution of a monoclonal antibody from a cation exchange chromatography device resulted in significantly sharper and narrower eluted protein peaks. Improvement in pH control during elution would not only result in better reproducibility and efficiency in separation but would also ensure greater stability of pH sensitive proteins during their purification using ion exchange chromatography.