Preparation of Molecularly Imprinted Polymer Microspheres for Selective Solid-Phase Extraction of Capecitabine in Urine Samples

Molecularly imprinted solid-phase extraction to treat biological samples has attracted considerable attention. Herein, molecularly imprinted polymer (MIP) microspheres with porous structures were prepared by a combined suspension-iniferter polymerization method using capecitabine (CAP) as a template molecule. This material was subsequently used as a solid-phase extraction agent to separate and enrich drug molecules in urine samples. UV analysis revealed that methacrylate (MAA) was an ideal functional monomer, and 1H Nuclear Magnetic Resonance ((1)H NMR), Ultraviolet (UV), and Fourier transform-infrared (FT-IR) spectroscopic analyses were used to study the interaction forces between MAA and CAP, demonstrating that hydrogen bonding was the primary interaction force. MIPs with outstanding selectivity were successfully prepared, and the analysis of their surface morphology and chemical structure revealed a spherical morphology with small holes distributed across a rough surface. This surface morphology significantly reduced the mass transfer resistance of template molecules, providing an ideal template recognition effect. Using the molecularly imprinted solid-phase extraction method, CAP and the structural analog cytidine (CYT) were pretreated in urine samples and quantified by HPLC. The results showed that CAP and CYT recoveries reached 97.2% and 39.8%, respectively, with a limit of detection of 10.0–50.0 µg·mL(−1). This study provides a novel approach to drug molecule pretreatment that can be applied in drug separation and functional materials science fields.