The use of boronate derivatives in the characterization of catecholamines and related β-hydroxy-amines by gas liquid chromatography-mass spectrometry

Abstract

Abstract The gas chromatographic separation of various β-hydroxy-amines in the form of derived 1, 3, 2-oxazaborolidines is complemented by a mass-spectrometric study of cyclic boronates of natural catecholamines. These derivatives and their synthetic analogues yield characteristic mass spectra. Closely similar compounds, such as the n-butylboronates of the diastereoisomers (—)-ephedrine and (+)-ψ-ephedrine, give almost identical spectra but can be readily distinguished by their glc retention times. The same can be said for the positional isomer pairs synephrine and phenylephrine, and for octopamine and 4-deoxynoradrenaline. Mass-spectrometric fragmentation modes are postulated from a comparison of the shifts in the masses of fragment ions corresponding to various substituents in the group of biological amines studied. Additional correlations are derived from studies of methyl-, cyclohexyl- and phenyl-boronates.