The isolation and purification of sufficient quantities of heparin-derived oligosaccharides for characterization by NMR is
a tedious and time-consuming process. In addition, the structural complexity and microheterogeneity of heparin makes its characterization
a challenging task. The improved mass-sensitivity of microcoil NMR probe technology makes this technique well suited for characterization
of mass-limited heparin-derived oligosaccharides. Although microcoil probes have poorer concentration sensitivity than conventional
NMR probes, this limitation can be overcome by coupling capillary isotachophoresis (cITP) with on-line microcoil NMR detection
(cITP-NMR). Strategies to improve the sensitivity of on-line NMR detection through changes in probe design and in the cITP-NMR
experimental protocol are discussed. These improvements in sensitivity allow acquisition of cITP-NMR survey spectra facilitating
tentative identification of unknown oligosaccharides. Complete structure elucidation for microgram quantities of the purified
material can be carried out through acquisition of 2D NMR spectra using a CapNMR microcoil probe.
Survey NMR spectrum obtained by cITP-NMR using a second-generation probe (the microcoil of which is shown) facilitates tentative
identification of unknown oligosaccharides (e.g., the heparin-derived tetrasaccharide illustrated)
Keywords Heparin - Microcoil - NMR - Capillary isotachophoresis - Glycosaminoglycans - Structure elucidation