Selective Sensing of Perfluorooctanesulfonic Acid in Food Samples Using Functionalized Poly(2-oxazoline)-Based Molecularly Imprinted Polymers

Perfluorooctanesulfonic acid (PFOS) is a persistent organic pollutant frequently detected in food and environmental samples, posing significant health risks. This study presents an approach for the selective detection and quantification of PFOS in food samples using functionalized poly(2-oxazoline)-based molecularly imprinted polymers (MIPs) coupled with flowing atmospheric pressure afterglow mass spectrometry (FAPA-MS). The MIPs were prepared based on a poly(2-allylamidoethyl-2-oxazoline) precursor polymer that was partially functionalized with different thiols through radical thiol-ene "click" chemistry, followed by cross-linking with bis(2-mercaptoethyl)ether in the presence of PFOS as a template. The resulting MIPs, functionalized with alkyl, hydroxyl, carboxyl, and perfluoroalkyl groups, demonstrated high selectivity and adsorption capacity for PFOS, with carboxyl- and perfluoroalkyl-functionalized MIPs showing the highest adsorption capacities of 375 and 406 mg g- 1, respectively. It was demonstrated that the presence of the side-chain amide groups in poly(2-allylamidoethyl-2-oxazoline) leads to more performant MIPs compared to analogues based on poly[2-(3-butenyl)-2-oxazoline]. The MIPs were applied to analyze PFOS in real-life food samples. The detection limits (LODs) for PFOS in these matrices were as low as 5 ppb, with excellent recovery rates. The method exhibited high precision, with relative standard deviations (RSDs) below 8.2% for intraday and interday measurements. This study demonstrates the effectiveness of poly(2-allylamidoethyl-2-oxazoline)-based MIPs for sensitive and selective PFOS detection in complex food matrices, offering a robust tool for food safety and environmental monitoring.