A Two‐Speed Centrifuge for Immunohematologists

In an effort to produce a more softly packed “button” of cells during centrifugation, a fixed speed centrifuge was modified to provide a second lower speed to be used for final centrifugation. Several of these were tested and it was found that centrifugation of the cells suspended in albumin at 2,000–2,500 rpm (400–500 R.C.F.) for two minutes produced comparable results to centrifugation at 3,420 rpm (1,000 R.C.F.) for 30 seconds, but gave a less densely packed “button.” These “buttons” produced less false positive readings and were easier to interpret. Saline and albumin globulin titers were the same at all speeds and time intervals.