Molecularly imprinted polymers for selective separation of acetaminophen and aspirin by using supercritical fluid technology

In this study, we synthesize molecularly imprinted polymers (MIPs) by using supercritical fluid technology in carbon dioxide (CO2). To prepare MIPs, methyl methacrylate (MMA) is used as a third monomer, methacrylic acid (MAA) or 4-vinylpyridine (4-VP) as functional monomers, acetaminophen (AAP) and aspirin (AS) as templates, and ethylene glycol dimethacrylate (EGDMA) as a crosslinker. To evaluate the binding characteristics of MIPs for AAP and AS, equilibrium binding experiments are conducted. The results indicate that the adsorption equilibrium time is about 120 min, and the binding amount increases with the concentration of templates. The adsorption ability of the MIPs is also investigated by performing an HPLC analysis, measuring the adsorbed amounts for templates and their structural analogue, the selectivity factor (α), and the imprinting-induced promotion of binding (IPB). The results of the evaluation analysis indicate that the prepared MIPs have high separation abilities and selectivity. In addition, the molecular recognition properties according to the kind of functional monomers (MAA and 4-VP) and polymerization methods indicate that the use of 4-VP as a functional monomer is more efficient for binding yield and affinity, and the MIPs prepared by using supercritical fluid assisted polymerization are more efficient way to selectively separate and detect templates than bulk and emulsion polymerization process.