The Reason for Increase of Column Pressure During Use

Flash column pressure has something to do with the form of silica gel, the mesh number, the synthesis condition of filler, the condition of column packing, the mobile phase, and the temperature when analyzing.

For different manufacturers’ new flash columns (such as Spherical Diol Flash Column and Spherical Phenyl Flash Column) their column pressures may be differed by 4 to 5 Mpa under the same condition of mobile phase and temperature. Especially for the low-end and high-end products, the difference is more obvious.

Form of silica gel: The form of silica gel used in the flash column, such as irregular or spherical particles, can influence the pressure. Irregular particles may have more significant void spaces between particles, leading to higher pressure compared to spherical particles.

Mesh number: The mesh number refers to the size of the silica gel particles in the flash column. Smaller mesh numbers indicate larger particle sizes. Columns with larger particle sizes generally have lower pressure compared to those with smaller particle sizes.

Synthesis condition of filler: The synthesis condition of the filler material, such as the surface area, pore size distribution, and packing density, can affect the pressure during flash chromatography. These characteristics influence the flow dynamics and the resistance to solvent flow, thereby impacting the pressure profile.

Column packing: The quality of column packing, including the packing density and uniformity, can impact the pressure. Well-packed columns with a consistent bed density generally exhibit lower pressure compared to poorly packed columns with uneven packing or voids.

Mobile phase: The composition and viscosity of the mobile phase used in flash chromatography can affect the pressure. Solvents with higher viscosities or mixtures with higher proportions of viscous solvents can lead to increased pressure.

Temperature: The temperature at which the flash chromatography is performed can influence the pressure. Changes in temperature can affect the viscosity of the mobile phase and the analyte’s solubility, thereby impacting the pressure profile.

It is important to consider these factors and optimize the flash column and experimental conditions to achieve efficient separation with minimal pressure buildup. Adjusting the column packing, selecting an appropriate mesh number, optimizing the mobile phase composition, and controlling the temperature can help manage the column pressure during flash chromatography.

The above-mentioned is decided by the silica gel and production condition of the manufacturers, and the existence of difference is very normal. At the same time, column pressure also has something to do with column efficiency. In general, the flash column with high column efficiency has relatively high column pressure, while the flash column with high column pressure does not always have high column efficiency.

Normally, there are two types of pressure increase during the use of a flash column. One is that the column pressure increases slowly as the time of use extends, and this is normal. The other is that the column pressure suddenly increases a lot during use. This phenomenon is always caused by the improper operation of laboratory workers. They mainly do not filter the samples before using the flash column.