Fragmentation behavior of DOTA complexes under different activation conditions

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Coordination Chemistry

Background:

• DOTA-metal complexes are crucial in various applications, including medical imaging and therapy.
• Understanding their fragmentation behavior is key to characterizing these complexes and their stability.

Purpose of the Study:

• To investigate the fragmentation pathways of DOTA-metal complexes under different activation conditions.
• To identify fragment ions and elucidate fragmentation trends based on metal properties.
• To explore water capture mechanisms during dissociation.

Main Methods:

• Electrospray ionization (positive and negative ion modes).
• Collision-induced dissociation (CID), infrared-multiphoton dissociation (IRMPD), and higher-energy collisional dissociation (HECD).
• High-resolution accurate mass measurements for elemental composition determination.
• Deuterium labeling experiments.

Main Results:

• Characteristic fragment ions were observed for DOTA-metal complexes under all activation methods.
• Elemental compositions of fragment ions were unambiguously identified.
• Fragmentation trends correlated with metal size and periodic table location (e.g., CO2, alkyl, amine eliminations).
• Lanthanide, aluminium, and indium species with even oxidation states or radicals were detected.
• Water capture during activation was investigated using deuterium labeling.

Conclusions:

• Fragmentation analysis provides valuable insights into the structure and stability of DOTA-metal complexes.
• Metal properties significantly influence fragmentation pathways.
• The study establishes a foundation for the structural characterization of novel DOTA-metal complexes using mass spectrometry.