Blood is collected into a plastic bag for blood collection & storage which contains anticoagulant/buffers etc. which allow storage of blood. These include citrate-phosphate dextrose (CPD), acid-citrate dextrose (ACD), ACD or CPD with adenine to prolong red cell storage, and other preservative solutions like SAGM etc. If red cells are preserved in SAGM solution then their life goes upto 42 days. The CPD solution preserves whole blood for 21 days whereas CPDA solution preserves blood for 35 days. The material of the bag is biocompatible with blood cells and allows diffusion of gases permitting optimal cell preservation. The specimen thus collected is tested for hepatitis B & C, HIV and other infections. The blood is stored in refrigerators at 2 to 6 degrees C. Each unit of whole blood normally is separated into several components. Red blood cells may be stored under refrigeration for a maximum of 42 days, or they may be frozen for up to 10 years. Red cells carry oxygen and are us...