Selective sorption of hippuric acid and 4-methylhippuric acid by polyethylene glycol modified ZIF based molecular imprinted polymer

A novel solid phase extraction (SPE) adsorbent, polyethylene glycol (PEG) immobilized zirconium ion-modified zeolite-imidazole framework (ZIF) molecular-imprinted polymer (ZIF@PEG@Zr@MIPs), was developed for detecting hippuric acid (HA) and 4-methylhippuric acid (4-MHA) in human urine using HPLC-UV. Zirconium ions (Zr4+) anchored on the porous ZIF act as binding sites, facilitating coordination and electrostatic interaction with HA and 4-MHA carboxyl groups. Dopamine (DA) imprinting introduces additional sites, enabling π-π conjugation and hydrogen bonding with HA and 4-MHA, enhancing specific adsorption. The adsorbent, using HA as a template, demonstrated adsorption capacities of 37.98 mg g−1 for HA and 32.99 mg g−1 for 4-MHA. Imprinted factors (IF) were 2.68 for HA and 2.17 for 4-MHA, with a limit of detection (LOD) of 0.015 mg L−1 for HA and 0.011 mg L−1 for 4-MHA. The SPE-HPLC-UV method achieved 84.8–96.2% recovery and 0.3–2.2% relative standard deviation (RSD), illustrating its potential in health monitoring and environmental safety.