Quantifying trifluoroacetic acid as a counterion in drug discovery by 19F NMR and capillary electrophoresis.

Drug discovery compounds are often isolated as salts of trifluoroacetate from preparative high performance liquid chromatography, which are then used for biological assays in order to assess their efficacy against the biochemical target of interest. It is, therefore, imperative to determine the TFA content in order to ascertain the correct formula weight and when required, to ensure that the TFA has been completely exchanged for another counterion in order to have superior pharmacokinetic properties and to avoid potential toxicity effects. In this paper, we present capillary electrophoresis and (19)F nuclear magnetic resonance methods for determining the TFA content of drug discovery compounds. Furthermore, these methods have been successfully applied in a high-throughput fashion, which is a key feature for general applicability in a pharmaceutical setting.