What is the final step in labeling RBC with Cr51 before re-injecting?

Adding ascorbic acid to the tagged red blood cells (RBC) is crucial in the labeling process with Chromium-51 (Cr-51). The primary function of ascorbic acid is to act as a reducing agent. During the labeling process, any free Cr-51 ions can potentially interfere with imaging results or cause cell damage. By adding ascorbic acid, you help to stabilize the tagged RBCs and prevent aggregation, which can compromise the accuracy of the imaging outcomes when these cells are re-injected into the patient.

This step ensures that the labeled RBCs remain viable and that the radioactivity measured during the imaging accurately reflects the circulation of the re-injected cells, rather than any unbound or aggregated chromium. Consequently, this final step is essential for obtaining reliable and interpretable results in nuclear medicine studies involving tagged RBCs.