SiO2-Crosslinked Molecularly Imprinted Hybrid Nanostructures for Solid-Phase Extraction of Bisphenol A

Abstract

Previously, a molecularly imprinted hybrid (MIH) was synthesized by imprinting bisphenol A (BPA) within SiO2-crosslinked poly(styrene-co-methyl methacrylate) nanoframeworks. In this work, its adsorption and solid-phase extraction (SPE) performance toward BPA in complex matrices was systematically investigated and compared with two commercial sorbents, C18 and SupelMIPBPA. MIH exhibited a high adsorption capacity of 49.5 mg/g with a large Langmuir coefficient (KL = 3.16 × 10−2 L/mg) and high BPA selectivity with factors of 1.53 and 35.4 relative to 2BPF and phenol, respectively. Moreover, it exhibited 12 and 1120 times higher specific adsorption ability than SupelMIPBPA and C18, respectively. The tailored binding sites embedded within the hydrophobic polymeric matrix and stabilized with rigid, hydrophilic SiO2 crosslinks contributed to stable adsorption over pH 2−9 and in the presence of humic acid up to 20 mg/L while enhancing BPA adsorption by 1.5-fold at NaCl concentrations up to 3000 mM. MIH maintained stable adsorption over 11 regeneration cycles across synthesis batches and retained its adsorption capacity after more than six months of storage. When applied to SPE, the optimized MIH-SPE method effectively enriched BPA while reducing matrix interference, achieving enrichment factors of 52.0−60.0. Coupled with HPLC-photodiode array detection, the method achieved matrix-specific MDLs of 1.3 ng/mL in DI water and 0.2−3.1 ng/mL in environmental waters. Recoveries of 88.8−118.7% and RSDs of 0.2−9.6% demonstrated satisfactory accuracy and precision across the tested water matrices. In contrast, C18- and SupelMIPBPA-based SPE exhibited inferior performance due to limited adsorption capacity or less efficient analyte elution.