A separation system comprising a blood separation device containing a controller, a red-blood-cell (RBC) detection module, and a pump driver； and a cartridge configured to be reversibly attached to the blood separation device, the cartridge including: (i) a first container configured to contain a blood sample, wherein the first container includes a first opening； (ii) a tubing in fluid flow communication with the first opening； (iii) a pump in fluid flow communication with the tubing, wherein the pump is configured to move a fluid from the first container to the pump and to contain a fluid； and (iv) a check valve mounted to the tubing, wherein the check valve is configured to allow a fluid to flow from the first container to the pump and to not allow a fluid to flow from the pump to the first container.
