What is 20 column volume?

In the context of chromatography or column-based purification techniques, a "20 column volume" refers to a volume of solvent or eluent that is equivalent to 20 times the volume of the column's packing material. This measurement is often used to determine the amount of solvent needed for flushing, equilibrating, or eluting compounds from the column. For example, if a column has a volume of 10 mL, a 20 column volume would be 200 mL of solvent. This ensures thorough cleaning or elution of substances within the column.