Carbohydrate Separation Using the Core-Shell Ion-Exchange Resin St-80 with Different Numbers of Methylene Groups in the Porous Shell and a Constant Cross-Linking Degree

Clarifying the relationship between the molecular structure of ion-exchange resins and the elution of carbohydrates is essential for analyses using high-performance liquid chromatography (HPLC). From the perspective of novel resin development, we evaluated the effect of the number of methylene groups in the functional chain of the porous polymer shell on carbohydrate separation. Core-shell ion-exchange resins with a monomer weight ratio of 20:80 (denoted as St-80) were synthesized with a constant cross-linking degree of 55%. The number of methylene groups in the functional chain of the porous polymer shell was varied from two to six for analyses of carbohydrate separation performance under strong alkaline conditions. A mixture of inositol, glucose, fructose, and sucrose was separated using a 0.10 or 0.15 mol/L NaOH eluent at flow rates of 0.3–0.7 mL/min. The retention times were compared among St-80 variants with different numbers of methylene groups in the porous layer. As the number of methylene groups increased, the retention times of each carbohydrate for St-80(Me:4) at flow rates of 0.3–0.7 mL/min with 0.10 mol/L NaOH eluent increased slightly. The theoretical plate numbers of glucose and fructose at flow rates of 0.5 and 0.7 mL/min decreased as the number of methylene groups decreased from six to two. These results suggest that St-80 core-shell ion-exchange resins are highly efficient for carbohydrate analyses. Their suitability for strongly alkaline conditions allows their effective use in electrochemical detection.