Analysis of κ-Carrageenan Oligosaccharides by LC-ESI-MS/MSn with 3-Amino-9-ethylcarbazole Derivatization

A series of kappa-carrageenan oligosaccharides were prepared by using hydrochloric acid hydrolysis. The kappa-carrageenan oligosaccharides derivatized with 3-amino-9-ethylcarbazole (AEC) were analyzed by high performance liquid chromatography (HPLC) and HPLC coupling with electrospray ionization ion-trap mass spectrometry (LC-ESI-MS). The HPLC separation was carried out on a reverse phase (RP) C-18 column (250 mm X 4.6 mm, 5 mu m) in a linear gradient mode, using acetonitrile and ammonium acetate aqueous solution (pH 4.5) as mobile phase and a ultraviolet (UV) detection at 254 nm. Furthermore, the structure of the kappa-carrageenan oligosaccharide was confirmed by multi-stage mass spectrometry (MSn). These results may be helpful to investigation in structure identification and structure-activity relationship of kappa-carrageenan oligosaccharides.