Studies on Purification of Clinic Dextran with Solvent out Crystallization Assisted Membrane Separation Technology
Dextran is a bacterial polysaccharide produced from sucrose and usually used for clinical treatment as one kind of polysaccharide drugs. A traditional separating method with ethanol was hardly to control strictly for the molecular weight distribution of dextran. Some quality problems and clinical side effects induced by the disproportion of molecular weight, had become the bottleneck of study and application of dextran.In this study, Solvent Out Crystallization assisted Membrane Separation (SOCMS) is a new separation method proposed for thepurification of dextran.Its purpose is to separate dextran and control itsmolecular distribution, and prepare dextran with high purity at the sametime.Primary research subjects and conclusions were summarized as follow:1.Chromatogram conditions to measure the molecular weight ofdextran were determined.2. By using uniform experiments design, several factors that influenced the solvent out crystallization were investigated.3. Through analyzing purification effects of ultrafiltration membranes with different molecular weight cut-off, it showed that membranes of 30KD and 5KD were helpful to the purification of dextran.4. The determination of membrane separation parameters was established by single factor experiment.5. By connection of ultrafiltration and reverse osmosis, purification process was optimized.6. Cleanig condition of membranes were determined.7. The purity of the purified sample samples was identified by the ultraviolet spectrum. The result showed that there were no protein, nucleic acid, pigment and mannose within them. Preliminary studies on the structure of purified samples by the infrared spectrum illuminated that purified samples were the same material with the dextran. Analysis on thermodynamic properties by DSC showed that purified samples were much more similar in composition.