We examined the performance of the selected BAs in differentiating between the following samples: 2,3 sialyllactose (3-SLA), 2,6 sialyllactose (6-SLA), and sialic acid monosaccharide mixed with lactose (SA+Lac). (structure information are shown in SI Figure ). 3-SLA consists of a sialic acid residue attached to galactose in lactose molecule with α2,3 linkage, and 6-SLA has a α2,6 linked sialic acid with lactose. To observe the influence of sialic acid without linkage, we mixed the equal molar concentrations of sialic acid monosaccharides with lactose.