Unexpected transformation of n.c.a. [111In]InCl3 in stock solutions into an unreactive [111In]In-species. (February 2022)

• Record Type: Journal Article
• Authors: Giammei, Carolina; Jouini, Nedra; Brandt, Marie R.; Frey, Stefanie; Mindt, Thomas L.; Cardinale, Jens
• Is Part Of: Applied radiation and isotopes. Volume 180(2022)
• Publication Date: 2022-02
• Subjects: Indium-111 -- DOTA 111In-labeling -- Transformation -- Impurities -- Radiochemical yield; Radiology -- Periodicals; Radiation -- Industrial applications -- Periodicals; Nuclear chemistry -- Periodicals; Internet resource; Periodical; 660.298
• DOI: 10.1016/j.apradiso.2021.110037
• Languages: English
• ISSNs: 0969-8043

Abstract

Abstract: While performing multiple indium-111 labeling of DOTA-modified peptides from a single batch of [ 111 In]InCl3, inconsistent radiochemical yields were observed. We found that the formation of a radioactive impurity in the [ 111 In]InCl3 stock solution hampered the reactivity of the indium-111 during radiolabeling reactions. The formation of this unknown 111 In-species could be successfully suppressed by increasing the concentration of chloride ions in the stock solution and [ 111 In]InCl3 was "recovered". Radiolabeling of DOTA-peptides with the stabilized [ 111 In]InCl3 resulted again in acceptable radiochemical yields. In addition, we report convenient iTLC systems that allow distinguishing between [ 111 In]InCl3, the formed unknown 111 In-species, radiocolloids, and radiolabeled peptides (DOTANOC). Highlights: The transformation of [ 111 In]InCl3 in commercial 111 In-solutions into a new unreactive species leads to reduced RCYs. Method to quantify the unreactive 111 In species by TLCs. Method to prevent the formation of unreactive 111 In-species and improve RCY.