During the actual operation, the process needs to be optimized based on the characteristics of the polypeptide (such as charge properties, molecular size, hydrophobicity, etc.) and the required purity. 

For small molecule polypeptides, the organic solvent precipitation method can be used for the initial purification, followed by further purification using ion-exchange chromatography or RP-HPLC. For polypeptides with specific biological activity, affinity chromatography can be given priority for high-precision purification. 

The separation and purification of small molecule peptide drugs is a complex and meticulous process. It requires comprehensive consideration of factors such as the characteristics of the peptide, the required purity, and production costs, and the selection of appropriate purification methods or combinations of multiple methods. 

At the same time, it is also necessary to pay attention to factors such as operational procedures, temperature control, and pH value adjustment during the purification process, in order to ensure the quality and stability of the final product. 

For many years, Wuhan Bona has been dedicated to the development of application processes for membrane separation technology. By integrating processes, membranes and equipment, it has accumulated rich experience in product purification and engineering scale-up. This has not only solved manufacturing challenges but also improved product quality, and together with customers, it has enhanced the technical level of the industry.