On-line separation and structural characterisation of feruloylated oligosaccharides from wheat bran using HPLC-ESI-MSn

Water-soluble feruloylated oligosaccharides (FOs) from wheat bran, ferulic acid esters of arabinoxylan oligosaccharides, have been reported as natural antioxidants. In this study, structure features of FOs were studied by FT-IR spectroscopy, and high-performance liquid chromatography (HPLC) coupled to electrospray ionisation (ESI) mass spectrometry (MS) was used for separation and characterisation of FOs. Four components of FOs were resolved on a Dikma Technologies Diamonsil™ C18 column eluted with water/acetonitrite (90:10) containing 0.5% HCOOH (V/V) and further analysed by ESI-MSn. In ESI-MSn, a predominant [M+NH4]+ ion in positive mode and [M−H]− ion in negative mode were observed for molecular mass information. The ESI-MSn spectra of the deprotonated molecular [M−H]− ion were used for structural elucidation. The structures of four isolated compounds were confirmed for the first time by on-line HPLC-ESI-MSn.