Systems and methods for separation of platelets from blood and return of mononuclear cells

A blood separation device for use in combination with a fluid flow circuit, comprising:

• a separator;
• a pump system;
• and
• a controller configured to
• (a) determine a volume of blood to be processed, and/or a volume of platelets to be collected, and/or a time at which to complete blood draw, and/or a time required to complete blood draw from a source during a blood separation procedure,
• (b) select or determine a procedure setpoint calculated from the completion of the blood draw,
• (c) execute a blood separation procedure comprising
• operating the pump system to draw blood from a source into a separator,
• operating the separator to separate the blood in the separator into a platelet-containing fraction and a mononuclear cell-containing fraction,
• operating the pump system to convey at least a portion of the platelet-containing fraction from the separator while increasing a volume of the mononuclear cell-containing fraction in the separator, and
• operating the pump system to convey the mononuclear cell-containing fraction out of the separator to the source at the procedure setpoint, and
• (d) end blood draw.