Table 1.

Major advantages and drawbacks of the two methods.

	Advantages	Drawbacks
SAX-HPLC	Di- and tetra-saccharide composition: single building blocks identified and quantified	Digestion with a mix of Heparinases: the thorough yield of the depolymerization reaction should be confirmed (e.g., by Size Exclusion Chromatography)
	High Sensitivity: LOD 0.1%, LOQ 0.3% (for disaccharides that respond to the mixture of Heparinases)	Sequences with specific process signatures not cleaved by the enzymes
	Identification of specific disaccharides containing 6-O-sulfated glucosamine	Iduronic/glucuronic structure not distinguished. Information only about uronic acid-glucosamine sequences
	Easily achievable in every analytical lab; standard equipment	Saturated residues at the non-reducing end of heparin chains not detectable
		Quantification based on consensus assumption that all Δ4-5 unsaturated di- and oligo-saccharides have the same molar absorption coefficient
HSQC-NMR	No sample treatment necessary: information about the overall structure	Low sensitivity: specific for each residue. LOD 0.5%, LOQ 2% on average
	Mono- and di-saccharide composition	Possible problems with signals resolution
	Iduronic and glucuronic acids can be distinguished	Quantification possible only by comparison of atoms with similar magnetic properties
	Information about both uronic acid-glucosamine and glucosamine-uronic acid sequences	Only the overall 6-Osulfation of glucosamine residues can be determined*

^*The possibility of differentiating 6-O-sulfated and non-sulfated glucosamine by 1D proton NMR has been recently described (23). However, the resolution of the HSQC spectrum does not make it possible to resolve these peaks, if not at a very high magnetic field.