Abstract:This study investigated the yellow-brown anion exchange resin formed by ferric ion pollution in the purification process. The pigment is produced and aggravated under alkaline conditions, and cannot be removed by conventional methods such as high salt and surfactants. Phosphoric acid, acetic acid, citric acid and hydrochloric acid were used for testing in this study. It was found that concentrated phosphoric acid could remove resin pigments more effectively than citric acid, while concentrated acetic acid and hydrochloric acid could not. Based on the above conclusions, the effect of phosphoric acid on the pigment in the resin under different concentrations and treatment times was further studied. The results showed that the ferric ion concentration and resin capacity increased with the increase of phosphoric acid concentration, however, prolonging incubation time led to the increase ofresin capacity, but gradually decreased ferric ion concentration. Hence, it was inferred that during the treatment ofresin pigment with phosphoric acid, there was secondary adsorption of iron ions to the porous structure of resin lumen with the increase of incubation time, resulting in the gradual decrease of ferric ions in the solution. Through data analysis in combination with color contrast, it was determined that incubating anion exchange resins with 0.5 mol/L phosphoric acid for 8.75~11.35 minutes could significantly remove the stubborn pigment problems caused by ferric ions, and restored the resin capacity recover, while avoiding related impurities to pollute the final protein product. The new method for removing impurities in chromatography resin studied in this paper could provide a theoretical reference for the cost reduction and efficiency enhancement of related biological products in the downstream industrialization.
