In this method, patient or donor blood is collected and processed into an erythrocyte concentrate with a high hematocrit content.
A separate washing step will lead to the removal of plasma parts which will further purify and concentrate erythrocytes.
[citation needed] Other plasma and blood cell separation techniques are being explored based on magnetophoresis, electrophoresis, microchannel bends, and ultrasound standing waves.
The advantage to the donor is the use of smaller needles and saline compensation, as well as more convenient donating schedules (the no-donation period following apheresis is twice as long as that for a single unit).
The advantage to the blood bankers is the on-line separation into standardized RBC masses with the subsequent reduction in testing, data entry and staffing.