Evaluation of a Novel Ion-Exchange Resin, St-70, with a Cross-Linking Degree of 40% and Various Numbers of Methylene Groups in the Porous Shell

The complex relationship between the molecular structure of ion-exchange resins and carbohydrate elution presents a challenge for the development of polymer materials for high-performance liquid chromatography under a wide range of conditions. We evaluated the effect of the number of methylene groups in the functional chain of the shell on carbohydrate separation. Core-shell ion-exchange resins with a monomer weight ratio of 30:70 (denoted as St-70) were synthesized with a constant cross-linking degree of 40%. The number of methylene groups in the functional chain of the porous polymer shell was varied from two to six (denoted as St-70 (40% Me:2, 4, and 6)) to analyze the carbohydrate separation performance under strongly 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. As the number of methylene groups increased, glucose, fructose, and sucrose for St-70 (40% Me:4) at flow rates of 0.3-0.7 mL/min with 0.10 mol/L NaOH eluent showed the largest retention times. The carbohydrates for St-70 (40% Me:4) at flow rates of 0.3, 0.5, and 0.7 mL/min showed the largest theoretical plate numbers when the number of methylene groups was changed from two to six. These results suggest that St-70 core-shell ion-exchange resins are highly efficient for carbohydrate analyses. Their suitability under strongly alkaline conditions facilitates their effective use in electrochemical detection.