The General Guidelines Of The Flash Column Chromatography
When flash column works, the upper interface generally has a gas/liquid (with a certain pressure) to speed up the sample separation process. It operates at pressures of 50 -200 psi, as compared to HPLC, which operates at 1000s of psi, and UHPLC which operates above 10,000 psi. Flash column is the primary purification technique used in organic synthesis and industrial applications because it is fast (Flash!), it is easy to use and it is versatile.
The method of the flash column chromatography is to separate the components from the mixture and purify it. In short, fast column chromatography makes samples go through gel-filled columns, and the gels help make the separation. The founders of the fast column chromatography at first wanted to find a method to overcome the shortcomings of long column chromatography, such as time-consuming and low recovery.
The gel used initially for packing columns is silica gel, which is still widely used. People push solvents through silica gel flash columns by air pressure. And then they add the samples in it and push samples through the columns. The components needed to be collected and purified will appeared during the process of the elution.
Since the silica gel, flash column chromatography is widely used in organic chemistry, the guidelines are important when you try to get better sample quantity results. The flow rate depends on different column length and width, and the properties of the gel as well.
You can figure out that the longer and narrower columns will provide more theoretical plates, and slow the flow rate at the same time. And the resolution is also affected by the stationary phase. If the stationary phase or the gel which lines the column is more homogenous and has smaller particle size as well, you can get better resolution. Smaller particle size which means more surface area leads to a better resolution.
It’s very complex to control all these factors to optimize purity and recovery of components because the factors work with each other, but have different effects if tested individually. You can find mobile phase selectivity has the largest effect on the resolution, but it depends on the column capacity as well. the solvent that you choose can affect the resolution too.
The flash column chromatography has been widely used in organic chemistry since its advent. However, there are still some problems when using the method. The increasing sample size will result in a lower resolution. The best velocity depends on the length and width of the column and the properties of the gel. The resolution is affected by the stationary phase.
How does Flash column work
The working principle is the same as the liquid chromatography separation by selective adsorption and selective elution. The frequent used method is to pass the liquid sample solution through the adsorbent, retain the substance to be tested, and use the appropriate strength solvent to wash away the impurities, and then quickly elute the test substance with a small amount of solvent, thereby achieving the purpose of rapid separation, purification, and concentration. It is also possible to selectively adsorb the interfering impurities and let the measured substance flow out; or simultaneously adsorb the impurities and the tested substance, and then selectively elute the test substance with a suitable solvent.