Preparation of human hemoglobin Ao for possible use as a blood substitute

A procedure is presented for the preparation of a purified fraction of adult human hemoglobin (HbAo) from one unit of outdated blood. The entire process requires less than 16 h and gives a sterile, endotoxin-free solution of HbAo (approximately 30 g) in a yield of 50%. The solutions are isoionic with a conductivity of less than 15 mu mhos and less than 2 mmol total phosphorus per mol heme. The methemoglobin content is less than 1% and on storage at 4 degrees C rises less than 1% per month.