Mass spectral fragmentation analysis of triterpene saponins from Ardisia crenata Sims by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Abstract

We used the electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) technique to study the characteristic mass fragmentation patterns of eight triterpene saponins from Ardisia crenata Sims. Eight triterpene saponins were analyzed using parent mass list-triggered data-dependent multiple-stage accurate mass analysis at a resolving power of 100,000 in the external calibration mode. The chemical formula with unsaturation numbers was calculated from accurate m/z values of precursor, and product ions were obtained and used to assign the structures of eight triterpene saponins and two trace unknown compounds. The mass accuracies obtained for all full-scan MS and MS ⁿ spectra were within 7 ppm ( < 5 ppm in most cases) in the ESI negative-ion mode. On FTICR-MS and FTICR-MS/MS, the eight triterpene saponins showed characteristic mass fragmentation patterns that facilitated the identification of their structural types, including the individual monosaccharide types, the monosaccharide numbers, and the sequences of the substituted saccharide groups. We proposed their fragmentation mechanisms. Based on their characteristic mass fragmentation patterns and fragmentation mechanisms, two unknown trace triterpene saponins were identified in the mixture.

Keywords:

• Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS)
• triterpene saponins
• mass fragmentation
• Ardisia crenata Sims