Table I.

Sialic acid loss by reductive amination as determined by normal-phase HPLC

	α2,6 (%)	α2,3 (%)	Yield (%)
AB 1	1.7	4.9	90
AB 2	0.5	1.2	60
PA 1	13.6	81.9	95
PA 2	2	5.2	90

Derivatization of pure disialylated N-glycans (either Na^6–4Na^6–4 or Na^3–4Na^3–4) with 2-aminobenzamide was performed by the classical method [16] for 2 hours at 70°C (AB 1) or overnight at 37°C (AB 2). Derivatization with 2-aminopyridine was done by the original overnight method (PA 1) or by the modified mild procedure (PA 2) [16]. Derivatization yield was determined by ESI-MS.