Patent ID: 7176305

Claim:
A method of producing purine nucleotide disodium crystals, comprising: crystallizing a purine nucleotide disodium in a solution of alcohol comprising one member selected from the group consisting of methanol, ethanol, and mixtures of methanol and ethanol, to obtain purine nucleotide disodium crystals which contain an alcohol; performing solid-liquid separation of said purine nucleotide disodium crystals which contain an alcohol, to obtain separated purine nucleotide disodium crystals; overdrying said separated purine nucleotide disodium crystals, to obtain overdried purine nucleotide disodium crystals; and bringing said overdried purine nucleotide disodium crystals into contact with an aqueous solution which comprises a hydrophilic organic solvent, to control the humidity of the purine nucleotide disodium crystals under a predetermined humidity condition, wherein said hydrophilic organic solvent is at least one alcohol selected from the group consisting of methanol, ethanol, propanol, and mixtures thereof, to obtain purine nucleotide disodium crystals which have an alcohol content which is lower than said purine nucleotide disodium crystals which contain an alcohol.