What is the use of saline and mannitol in anticoagulant for blood storage?

What is the use of saline and mannitol in anticoagulant for blood storage?

When red cells are stored as suspensions in artificial preservative solutions such as those consisting of saline, adenine, and glucose, increased hemolysis of the red cells occurs in vitro, mannitol stabilise the membrane and it will prevent Hemolysis

Saline is for isotonicity,mannitol for decrease hemolysis of rbc (osmotic purgative) by decreasing swelling of rbc

Adenine -atp generation

Citrate- decrease ca++ decrease clot formation

Phospate - buffer ( rbc acidic on standing)