Enhanced electrophoretic resolution of monosulfate glycosaminoglycan disaccharide isomers on poly(methyl methacrylate) chips

To improve the separation of monosulfate glycosaminoglycan disaccharide isomers by microchip electrophoresis, we found that addition of 1,4-dioxane (DO) dramatically improved analyte resolution, probably due to solvation effects. Methylcellulose (MC) was tested for the ability to suppress EOF and analyte adsorption to the chip. To improve analyte resolution, buffer pH, β-CD, and DO were systematically investigated. Fast separation was achieved by increasing the electric field strength, and field-amplified sample stacking occurred with increasing buffer concentrations. Therefore, based on our findings, we describe an efficient method for the separation of mono-sulfate and trisulfate unsaturated disaccharides (ΔDi-UA2S, ΔDi-4S, ΔDi-6S, and ΔDi-triS) derivatized with 2-aminoacridone hydrochloride. A mixture of monosulfate disaccharide isomers (ΔDi-UA2S, ΔDi-4S, and ΔDi-6S) was baseline-separated within 75 s on a poly(methyl methacrylate) chip using a mixed buffer (DO /running buffer 57:43 v:v), 0.5% MC, pH 6.81, with an E_sep of 558 V/cm. The theoretical plate was in the range of 5 × 10⁵ to 1 × 10⁶ m^-1.