Filling method and precautions of chromatographic column
Chromatographic column is a widely used method in chromatography, and it is also one of the commonly used separation methods in organic experiments. This column is the main part of gel chromatography technology, and glass tube or plexiglass tube is generally used. A chromatographic method for separating components in the sample mixture according to their different distribution coefficients in the stationary and mobile phases. Column chromatography, also known as column chromatography, is mainly based on the different distribution coefficients of each component in the sample mixture in the stationary phase and mobile phase. The components are separated by repeated distribution.
The packing of chromatographic column is very important, and the packing effect will directly affect the chromatographic separation effect. There are two methods of column loading: wet method and dry method. The wet packing of the column is very simple, and it is also widely used, that is, first use the eluent twice as much as the stationary phase to activate the stationary phase into a homogenate, and then fill the bottom of the column with absorbent cotton, and then pour the eluent to drive out the bubbles in the absorbent cotton. Pour the live stationary phase into the column with a funnel, open the bottom piston, and discharge the solvent in the column higher than the stationary phase. During this period, the stationary phase shall be continuously knocked with a rubber stick to make it compact and even without bubbles. In many cases, the column can be effectively installed by pressurizing, and there is no bubble in the column.
The opposite of the wet method is that the dry adsorbent is directly added to an empty column from the upper end of the column, and then the bottom of the column is pumped, which is equivalent to decompression through the column until the column becomes very solid, and then the eluent is used to "walk the column". One disadvantage of dry column loading is that after the eluent is loaded, the column is easy to flower due to the adsorption and heat release between the solvent and the stationary phase, which affects the separation effect. The solution is: solid stationary phase must be added; Be sure to use more solvents to "walk the column" until the lower end of the column is no longer hot, and then remove the pressure after it recovers to room temperature. No matter which method is used to install the column, the column shall be solid, symmetrical and free of bubbles.