How To Prepare And Operate Flash Column Chromatography
To prepare and operate flash column chromatography, firstly, we should confirm the weight of mixture which is dry, solvent-free, and ready for separation. Secondly, we can use thin-layer chromatography to choose a solvent system and manage the Rf value between 0.2 to 0.3. However, if the mixture is complex, we may need to use gradient elution to continually improve the solvent’s polarity.
Afterward, we will confirm the methods of sample loading. Basically, there are three methods: sample cleaning method, solvent method, and silica gel adsorption method.
In addition, we should also confirm the appropriate proportion of silica gel and a chemical compound. As for simple separation, normally the proportion of silica gel and chemical compound should be 30/1 or 50/1 (proportion by weight). As for difficult separation, the proportion could be 120/1.
It is important to choose an appropriate flash column, and the quantity of silica gel we need to use decides the size of the flash column. Moreover, we should choose the appropriate collecting tube, and once the flash column is chosen, we need to block off the bottom of the piston to prevent the silica gel from running off.
Last but not the least, in consideration of the use of a large amount of volatile solvent, and dry silica gel which is harmful to people’s health, we must fill the flash column in the fuming cupboard.