Device for mobile phase velocity control across the diameter of a chromatography column

A chromatography column, comprising:

• a column wall;
• a column bed comprising a stationary phase material disposed inside the column wall and having an inlet end and an outlet end;
• an inlet end nut secured at the inlet end of the column bed;
• an outlet end nut secured at the outlet end of the column bed;
• and
• a first frit disposed between the inlet end of the column bed and the inlet end nut and a second frit disposed between the outlet end of the column bed and the outlet end nut, at least one of the first and second frits comprising a disk having a porosity, a radius and a thickness, the disk having at least one of a variation in the porosity in the in a radial direction and a variation in the thickness in the radial direction, wherein a flow of a liquid received at an inlet end of the disk is advanced at an outlet end of the disk in an outer region of the disk relative to the flow of the liquid in an inner region of the disk in response to the at least one of the variation in the porosity in the radial direction and the variation in the thickness in the radial direction.