Patent ID: 8900805

Claim:
A method of treating a red blood cell composition comprising: (a) mixing (i) an effective amount of a pathogen-inactivating compound comprising a functional group which is, or which forms, a reactive electrophilic group; (ii) an effective amount of a quencher comprising a thiol group, wherein the thiol is capable of reacting with the reactive electrophilic group of the pathogen-inactivating compound; (iii) a composition comprising red blood cells; and (iv) about 0.5 to 1.5 equivalents of base, wherein an equivalent means a molar amount that is equivalent to the molar amount of quencher in the mixture; in a treatment solution or diluent solution; wherein the treatment solution or diluent solution comprises one or more of dextrose, adenine, mannitol, citrate, and citric acid; and wherein the mixture of step (a) after addition of the treatment solution or diluent solution comprises between about 40 mM and 100 mM chloride ion; (b) replacing the solution used during treatment of the red blood cell composition in step (a) with a final additive solution, such that the concentration of the quencher in the mixture is decreased to less than about 10 mM, wherein the level of dehydration of the treated red blood cell composition is decreased relative to the level of dehydration of a red blood cell composition treated according to a method comprising step (a), but excluding step (b) and/or with 2.0 or greater equivalents of base.