In the course of characterising neoglycolipid products derived from mucin oligosaccharide alditols after periodate oxidation and coupling by reductive amination to the aminolipid dipalmitoylglycerophosphoethanolamine, we have obtained evidence that oxidative cleavage occurs specifically at the C4-C5 bond of core N-acetylgalactosaminitol. Two lipid-linked fragments thus obtained from each oligosaccharide alditol are well resolved on thin-layer chromatography and can be sensitively analysed by liquid-secondary-ion mass spectrometry to assign the sequence and branching patterns of oligosaccharides linked at C6 and C3 to the N-acetylgalactosamitol. These conclusions have been reached from detailed studies of the neoglycolipid derivatives of several oligosaccharides (di- to hexasaccharides) which were isolated from human meconium and characterised previously by MS and NMR studies as the free alditols.