Determination of the enantiomeric composition of 1-phenylethylamine based on its quenching of the fluorescence of 2,2′-dihydroxy-1,1′-binaphthalene

A novel method for the determination of the enantiomeric purity of 1-phenylethylamine is described. It is based on the differences observed in the efficiencies of the quenching of the fluorescence of a chiral acid, 2,2′-dihydroxy-1,1′-binaphthalene, by each enantiomer of 1-phenylethylamine, a non-fluorescent base. A diastereoisomeric complex is formed between the fluorescent acid in its excited state and the nonfluorescent base, and energy transfer takes place via charge transfer. A linear relationship between the efficiency of the energy transfer measured in terms of the quenching of the fluorescence of the acid and the enantiomeric composition of the non-fluorescent base has been shown, and a limit of detection of one enantiomer in the presence of another has been calculated to be 10%.