A method for characterizing collected red blood cells (RBCs) for transfusion, comprising: a. obtaining an RBC sample from the collected RBCs; b. determining values of biomarkers in the RBC sample by analytical analysis, wherein the biomarker values are concentration of hypoxanthine, concentration of adenine, ratio of hypoxanthine: adenine, ratio of glucose:lactate, ratio of Na +:K +; optionally one or more of concentration of inosine, ratio of inosine:adenine, concentration of pyruvate, and ratio of pCO 2:pH; c. matching the biomarker values to respective control values for the biomarkers taken at different storage time points; and; d. assigning a metabolic state to the RBC sample based on the values of the biomarkers which is one of a First Phase, a Second Phase or a Third Phase; wherein: • the RBC sample is First Phase when the ratio of glucose:lactate and the ratio of Na +:K + match the values on the control indicated for First Phase; and optionally when one or more of the concentration of inosine, the ratio of hypoxanthine: adenine, the ratio of inosine:adenine and the concentration of pyruvate match the values on the control indicated for First Phase; • the RBC sample is Second Phase when the ratio of hypoxanthine:adenine matches the value on the control indicated for Second Phase; and optionally when one or more of the concentration of inosine, and the ratio of inosine:adenine match the values on the control indicated for Second Phase; or • the RBC sample is Third Phase when the ratio of hypoxanthine: adenine, the concentration of hypoxanthine and the concentration of adenine match the values on the control indicated for Third Phase, and optionally when one or more of the ratio of pCO 2:pH, the ratio of inosine:adenine, and/or the concentration of inosine match the values on the control indicated for Third Phase; and e. recommending First Phase or Second Phase RBCs for transfusion. a. obtaining an RBC sample from the collected RBCs; b. determining values of biomarkers in the RBC sample by analytical analysis, wherein the biomarker values are concentration of hypoxanthine, concentration of adenine, ratio of hypoxanthine: adenine, ratio of glucose:lactate, ratio of Na +:K +; optionally one or more of concentration of inosine, ratio of inosine:adenine, concentration of pyruvate, and ratio of pCO 2:pH; c. matching the biomarker values to respective control values for the biomarkers taken at different storage time points; and; d. assigning a metabolic state to the RBC sample based on the values of the biomarkers which is one of a First Phase, a Second Phase or a Third Phase; wherein: • the RBC sample is First Phase when the ratio of glucose:lactate and the ratio of Na +:K + match the values on the control indicated for First Phase; and optionally when one or more of the concentration of inosine, the ratio of hypoxanthine: adenine, the ratio of inosine:adenine and the concentration of pyruvate match the values on the control indicated for First Phase; • the RBC sample is Second Phase when the ratio of hypoxanthine:adenine matches the value on the control indicated for Second Phase; and optionally when one or more of the concentration of inosine, and the ratio of inosine:adenine match the values on the control indicated for Second Phase; or • the RBC sample is Third Phase when the ratio of hypoxanthine: adenine, the concentration of hypoxanthine and the concentration of adenine match the values on the control indicated for Third Phase, and optionally when one or more of the ratio of pCO 2:pH, the ratio of inosine:adenine, and/or the concentration of inosine match the values on the control indicated for Third Phase; and • the RBC sample is First Phase when the ratio of glucose:lactate and the ratio of Na +:K + match the values on the control indicated for First Phase; and optionally when one or more of the concentration of inosine, the ratio of hypoxanthine: adenine, the ratio of inosine:adenine and the concentration of pyruvate match the values on the control indicated for First Phase; • the RBC sample is Second Phase when the ratio of hypoxanthine:adenine matches the value on the control indicated for Second Phase; and optionally when one or more of the concentration of inosine, and the ratio of inosine:adenine match the values on the control indicated for Second Phase; or • the RBC sample is Third Phase when the ratio of hypoxanthine: adenine, the concentration of hypoxanthine and the concentration of adenine match the values on the control indicated for Third Phase, and optionally when one or more of the ratio of pCO 2:pH, the ratio of inosine:adenine, and/or the concentration of inosine match the values on the control indicated for Third Phase; and e. recommending First Phase or Second Phase RBCs for transfusion.