A series of κ-carrageenan oligosaccharides were prepared by using hydrochloric acid hydrolysis. The κ-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) C₁₈ column (250 mm×4.6 mm, 5 μm) 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 κ-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 κ-carrageenan oligosaccharides.

Key words: κ-carrageenan oligosaccharides, 3-amino-9-ethylcarbazole, high performance liquid chromato- graphy coupling with electrospray ionization ion-trap mass spectrometry (LC-ESI-MS), mass spectrometry (MSⁿ)