Key Words of Filtration Terms

Filtration is a process in a chemical experiment, separating solids from liquids or gases through a filter medium. Only the fluid or the gas is allowed to pass, not the solid. And the key words of filtration terms can help you understand how the filter works.

Hydrophilic, called “water-loving”, refers to a filter's ability to absorb water.

Hydrophobic call as “water-hating”, refers to a filter's ability to repel water.

Bubble Point refers to the amount of air pressure. The pressure can force liquid from the largest wetted pore of the membrane.

Molecular Weight Cut Off (MWCO) is the lowest molecular weight solute, which is 90% retained by the membrane. if the sample loss is acceptable, we can choose a membrane with MWCO the same as the molecular weight of the solute for rapid filtration. But if you want to cut the loss of material of interest, the membrane MWCO must be less than the molecular weight of the compound.

Prewet is a useful step before aqueous filtrations. Hydrophobic membranes need to be specially wetted with chromatography-grade methanol, acetone, or compatible fluid with low viscosity and rinsed with water.