The development of novel core–shell resins with high sensitivity, resolution, and tunable separation performance is increasingly important for advanced chromatographic applications. A particular challenge is the complex relationship between ion-exchange resin structure and carbohydrate elution, which complicates polymer design for high-performance liquid chromatography.

To investigate the influence of cross-linking and methylene group number in the functional chain of the shell, core–shell ion-exchange resins with a monomer weight ratio of 20:80 (St-80) and a fixed cross-linking degree of 40% were synthesized. The length of the functional chain in the porous polymer shell was varied from two to six methylene groups St-80(40% Me: 2, 4, and 6) and evaluated for carbohydrate separation under strongly alkaline conditions. A mixture of inositol, glucose, fructose, and sucrose was separated using 0.10 or 0.15 mol/L NaOH eluents at flow rates of 0.3–0.7 mL/min. Resins with four methylene groups St-80(40% Me:4) exhibited the highest retention times and theoretical plate numbers, particularly at 0.7 mL/min with 0.10 mol/L NaOH, and consistently outperformed resins with two or six methylene groups under 0.15 mol/L NaOH. These findings demonstrate that St 80(40% Me:2, 4, and 6) resins provide efficient carbohydrate separations and are well suited for use under strongly alkaline conditions with electrochemical detection.