@article{oai:repo.qst.go.jp:00084713,
 author = {Ryota, Imura (University of Tokyo/JFE Engineering) and Hiroyuki, Ida (JFE Enginnering) and Ichiro, Sasaki and Noriko, Ishioka and Shigeki, Watanabe and Ichiro, Sasaki and Noriko, Ishioka and Shigeki, Watanabe},
 issue = {16},
 journal = {Molecules},
 month = {Aug},
 note = {Background: Deferoxamine B (DFO) is the most widely used chelator for labeling of zirconium-89 (89Zr) to monoclonal antibody (mAb). Despite the remarkable developments of the clinical 89Zr-immuno-PET, chemical species and stability constants of the Zr-DFO complexes remained controversial. The aim of this study was to re-evaluate their stability constants by identifying species of Zr-DFO complexes, and demonstrate that the stability constants can estimate radiochemical yield (RCY) and chelator-to-antibody ratio (CAR). (2) Methods: Zr-DFO species were determined by UV and ESI-MS spectroscopy. Stability constants and speciation of the Zr-DFO complex were re-determined by potentiometric titration. Complexation inhibition of Zr-DFO by residual impurities was investigated by competition titration. (3) Results: Unknown species, ZrHqDFO2, were suc-cessfully detected by nano-ESI-Q-MS analysis. We revealed that a dominant specie under radio-labeling condition (pH 7) was ZrHDFO and its stability constant (logβ111) was 49.1±0.3. Competi-tion titration revealed that residual oxalate inhibits Zr-DFO complex formation. RCYs in different oxalate concentration (0.1 and 0.04 mol/L) were estimated to be 86% and >99%, which was good agreement with reported results (87%, 97%). (4) Conclusion: This study succeeded in obtaining accurate stability constants of Zr-DFO complexes, and estimating RCY and CAR from accurate stability constants established in this study.},
 title = {Re-evaluations of Zr-DFO Complex Coordination Chemistry for the  Estimation of Radiochemical Yields and Chelator-to-Antibody Ratios of 89Zr  Immune-PET Tracers},
 volume = {26},
 year = {2021}
}