Isolation of individual capsaicinoids from a mixture and their characterization by 13C NMR spectrometry

Abstract Individual compounds were isolated from a laboratory mixture of capsaicinoids by a multi-stage approach. First, the capsaicinoids were fractionated into capsaicins and non-capsaicins by argentation solid phase extraction (SPE) on a silver-charged propyl sulfonate resin. Second, compounds in each fraction were isolated by semi-preparative liquid chromatography on a C 30 phase in aqueous methanol. Third, the individual components of the original mixture were concentrated by reversed phased (C 18 ) SPE. The structure of each purified compound was confirmed by 13 C NMR spectrometry and spectral comparison to known standards, purchased or synthesized locally. The chemical shifts of 15 capsaicinoid standards were measured on a 600 MHz instrument, and their assignments to particular carbons were made by reference to Distortionless Enhancement by Polarization Transfer (DEPT) NMR experiments and NMR spectral prediction software.