Flash Columns Related Q&A
Since the introduction of silica gel flash column chromatography, it has been widely used in organic chemistry. Increasing the sample size results in reduced resolution. Compared with high-performance liquid chromatography (HPLC), the resolution of flash column chromatography is already at a medium level, but it is sufficient for sufficient separation, so an increase in quantity will only make the situation worse.
Second, the optimal flow rate depends on the length and width of the column and the nature of the gel. This is due to the number of plates available, for example, longer and narrower columns will provide a larger number of theoretical plates, which will affect the flow rate.
Finally, the resolution is affected by the stationary phase.
It provides a better resolution if the stationary phase or gel arranged on the column is more uniform and has a smaller particle size. The smaller the particle size, the larger the surface area and the higher the resolution. Now, we summarize the problems and methods encountered in the use of flash columns.
Q1：Could the silica-based normal-phase flash column be used repeatedly?
A：The silica-based normal-phase flash column can be used only once. However, if it is maintained properly it can be used again with good performance. The column needs to be dried by the compressed air or filled with isopropanol in order to be used again.
Q2: Could the silica-based flash column be eluted with methanol?
A: It is not recommended to use more than 25% methanol as eluent on the normal phase flash column.
Q3: What are the limitations of using polar solvents such as DMSO and DMF?
A: Generally speaking, the maximum tolerance concentration of solvents such as DMSO and DMF is 5%.