The influence of polysorbate 80 on the radiochemical synthesis of a PET tracer in the FASTlab.

ABSTRACT

PURPOSE: The aim of current study was to investigate the influence of a common non-ionic surfactant, polysorbate 80 (PS80), on radioactive labelling process of a novel PET tracer, [(18)F]Flutemetamol. METHODS: Ferrous oxidation-xylenol orange (FOX) assay, in addition to UV/VIS and (1)H NMR spectroscopies were applied to characterise the composition of the PS80 solution after storage. Multivariate Curve Resolution (MCR) and PLS analysis was used to establish correlation between quality of the PS80 solution and the RCP obtained after labelling. RESULTS: The levels of unsaturated fatty acid moieties of PS80 were negatively correlated to RCP of [(18)F]Flutemetamol after synthesis. This explains the slight increase in RCP when stored PS80 solutions were applied in the synthesis. The mechanism behind this observation is suggested to be related to radiation induced radical formation in the unsaturated fatty acids, which subsequently causes instability of the PET tracer. UV/VIS spectroscopy was demonstrated to have the ability as a possible control tool for quality assurance of the studied radioactive labelling process. CONCLUSIONS: The presence of unsaturated fatty acid moieties in PS80 was found to be one of the most important factors responsible for the reduction in RCP of [(18)F]Flutemetamol after synthesis.