A fluoro versus a nitro derivative - a high-performance liquid chromatography study of two basic analytes with different RP and silica phases as basis for the separation of a positron emission tomography radiotracer


A fluoro versus a nitro derivative - a high-performance liquid chromatography study of two basic analytes with different RP and silica phases as basis for the separation of a positron emission tomography radiotracer

Wenzel, B.; Günther, R.; Brust, P.; Steinbach, J.

To optimize the semi-preparative separation of a 18F-labeled PET radiotracer from its nitro precursor in a recently developed radiosynthesis, we performed an analytical HPLC study using the unlabeled reference compound and the corresponding nitro precursor. Several RP phases as well as a bare silica column were investigated with ACN and MeOH as organic modifiers and aqueous NH4OAc because of the basic character of the analytes. Four types of separation were observed based on different interaction mechanisms. When ACN/20 mM NH4OAc aq. was used mainly cationic-exchange and hydrophobic interactions contribute to the retention. A reversal of elution order could be observed starting from 95% ACN and subsequent increasing of the water content. This phenomenon was observed for all RP phases and seems to be independent of the different spacers bound to the silica. By contrast, using MeOH/20 mM NH4OAc aq. the elution order depends on the phase material. Two columns with the potential to perform π-π interactions showed different separation behavior compared to the other RP phases.

Keywords: Basic analytes; Cationic-exchange; RP phases; Silanol sites; VAChT

Permalink: https://www.hzdr.de/publications/Publ-18479
Publ.-Id: 18479