Dual-functional molecularly imprinted polymers for the selective removal and Ultrasensitive FAPA-MS detection of...

This study introduces molecularly imprinted polymers (MIPs) based on a polyethyleneimine (PEI) backbone for their selective removal and detection. To enhance molecular recognition, the PEI was pre-functionalized with 3,4-dichlorophenyl isocyanate (3,4-DCPI) at varying degrees (0-30%) before cross-linking. This significantly improved adsorption, with the most functionalized MIPs achieving high maximum capacities of 466 mg g^-1 for picloram and 282 mg g^-1 for diclofenac, significantly outperforming conventional methacrylic-based MIPs prepared for comparison. Adsorption kinetics followed the pseudo-first-order model, and isotherms fit the Langmuir model; the process was found to be spontaneous and exothermic. The MIPs demonstrated excellent selectivity, achieving selectivity factors of up to 6.14 for picloram and 9.22 for diclofenac against challenging structural analogs (including ibuprofen and naproxen), and maintained high performance with only ∼13% reduction in capacity over five adsorption-desorption cycles. When coupled with flowing atmospheric-pressure afterglow mass spectrometry (FAPA-MS) as a solid-phase extraction medium, the MIPs lowered the limits of detection to 0.03 μmol dm^-3 (picloram) and 0.076 μmol dm^-3 (diclofenac). The method's robustness was validated in spiked river water and bovine plasma samples, showing excellent accuracy and precision in both environmental and biological matrices, presenting a versatile platform for remediation and sensitive analytical applications.