Analysis of oligoguluronic acids with NMR electrospray ionization–mass spectrometry and high-performance anion-exchange chromatography

Oligoguluronates were prepared by enzymatic hydrolysis of homopolymeric blocks of guluronic acids. Two different oligosaccharides were prepared by separating final hydrolysates on Q-Sepharose FF ion chromatography. High-performance anion-exchange chromatography analysis showed the high purity of these oligosaccharides. The molecular masses of these two oligosaccharides, determined by electrospray ionization–mass spectrometry, were 396 and 594, respectively. 1H, 13C NMR, H-H COSY and HSQC analysis proved that they were the unsaturated dimer and trimer oligoguluronates. The 1H and 13C NMR chemical shifts of these two oligosaccharides are also reported.