A kit for labeling a prostate-specific membrane antigen (PSMA) ligand with a radioactive isotope such as 68Ga, 177Lu, or 90Y. Radiolabeled PSMA ligands prepared by this kit can be used for both imaging and therapy purposes. The kit includes a disposable reaction vial containing predetermined amounts of a sodium-based buffering agent and a PSMA ligand, both in dried form； or two disposable reaction vials, wherein one of the reaction vials contains predetermined amounts of the sodium-based buffering agent in dried form and the other of the reaction vials that contains predetermined amounts of the PSMA ligand in dried form, wherein the reaction vial containing the PSMA ligand and optionally the sodium-based buffering agent further contains protons adhered to the inner walls of the reaction vial.
