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anpeng木蟲 (著名寫手)
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[交流]
【求助】Help: PEG Purification 已有5人參與
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求助：聚乙二醇400的純化方法。 下面引自Purification of Laboratory Chemicals 6th Edition PEG is available commercially as a powder or as a solution in various degrees of polymerization depending on the average molecular weight, e.g. PEG 400 and PEG 800 have average molecular weights of 400 and 800, respectively. They may be contaminated with aldehydes and peroxides. Solutions deteriorate in the presence of air due to the formation of these contaminants. Methods available for purification are as follows: Procedure A: A 40% aqueous solution of PEG 400 (2 L, average molecular weight 400) is de-aerated under vacuum and made 10mM in sodium thiosulfate. After standing for 1 hour at 25°C, the solution is passed through a column (2.5×20 cm) of mixed-bed R-208 resin which has a 5 cm layer of Dowex 50-H+ at the bottom of the column. The column was previously flushed with 30% aqueous MeOH, then thoroughly with H2O. A flow rate of 1mL/minute is maintained by adjusting the fluid head. The first 200 mL are discarded, and the effluent is then collected at an increased flow rate. The concentration of PEG solution is checked by density measurement, and it is stored (preferably anaerobically) at 15°C. 能不能用中文描述一下？ 關(guān)鍵是a column (2.5×20 cm) of mixed-bed R-208 resin和Dowex 50-H+是什么？ [ Last edited by anpeng on 2010-7-11 at 11:00 ] |
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