Synthesis of Novel Sulfobetaine-Type Adsorbents and Characteristics of Their Adsorption of Polar Solutes in Hydrophilic SPE

A novel hydrophilic adsorbent was synthesized by introducing a sulfoethylbetaine functional group to a methacrylate base resin. The physical properties of the adsorbent were measured by NMR and IR spectroscopy and acid-base titration. The results indicate that (1) the positive and negative charges of the adsorbent are in balance when a purified sulfobetaine reagent is used, (2) the amount of water in the first hydration layer is about 6.7% of the adsorbent mass when the adsorbent is in an aqueous solution with a high acetonitrile content, and (3) the sulfobetaine functional group is covalently bonded to the base resin through a tertiary amino group. The retention properties of hydrophilic solutes on the adsorbent were estimated by the solid phase extraction method. All ionic reference solutes such as nucleobases (uracil, adenine and cytosine), acids (acephate and levulinic acid) and zwitterions (tetracyclines) were entrapped and released by the adsorbent. However, it showed almost no retention for non-ionic polar solutes such as saccharides. The polar solutes retained on the adsorbent could be easily eluted by water except for levulinic acid and tetracycline, which are easily ionized.