Suspension medium for red blood cells comprising amino acids

A suspension medium or diluent solution for reagent red blood cells, comprising phosphate buffer, sodium chloride, glucose, adenine, at least one preservative, EDTA and glycine and a combination of two or more amino acids of any group, wherein the amino acids other than glycine are present in a concentration of 0.50 to 6.48 g/l resulting in a total osmolality of between about 100-700 milliosmol/kg for the suspension medium or diluent solution and the combination of two or more amino acids other than glycine in the suspension medium or diluent solution reduces the loss of specificity and non-specific retention of the reagent red blood cells, and maintains the integrity and functionality of the reagent blood cells.