Post-Crosslinked Hydrazidine-Functionalized Resorcinol-Formaldehyde Imprinted Polymer for Selective S-Ketorolac Recognition.

A new enantioselective molecularly imprinted polymer (MIP) was developed for recognizing S-ketorolac (S-KR), a model chiral acidic drug. The synthetic process started with a resorcinol-formaldehyde resin (RSF), which was cyanoethylated under phase-transfer catalytic conditions to obtain RSF-CN. Then, the nitrile groups turned into cationic/basic hydrazidine sites after reacting with hydrazine hydrate, resulting in RSF-HD. Next, S-KR was interacted with RSF-HD in a DMF/water solution at pH 7, before adding glutaraldehyde for post-crosslinker. After that, the S-KR template was removed to get the final S-KR-imprinted polymer (S-KR-P). Tests, such as elemental analysis and solid-state 13C NMR, verified each step. Adsorption tests showed a strong pH dependence, working best between pH 6 and 7. For isotherm studies, the maximum capacity for S-KR on S-KR-P was 525 mg/g, whereas R-KR had 252 mg/g. The non-imprinted polymers (NIPs) worked similarly for both, around 180 mg/g. The Langmuir model fits better than the Freundlich model, pointing to adsorption on defined binding sites. With a selectivity coefficient of about 12, it shows effective stereoselective recognition, making S-KR-P a great option for separating chiral ketorolac.