Ultrasensitive and Highly Selective o-Phenylenediamine Molecularly Imprinted Polymer for the Detection of 2,4-Dichlorophenoxyacetic Acid

Herein, we report an ultrasensitive and highly selective analytical methods to detect 2,4-dichlorophenoxyacetic acid (2,4-D) using an o-phenylenediamine based molecularly imprinted polymer (o-PD-MIP) sensor. Electrochemical Quartz Crystal Microbalance (EQCM) is used to investigate both the kinetics and the mass of the electropolymerized o-phenylenediamine. Additionally, successful removal of the template from the imprinted cavities is confirmed by comparing the XP spectra of imprinted and o-PD-MIPs after various template removal procedures. The most effective method involves a 70:30 mixture of MeOH:H₂O for 15 min under stirring. The o-PD-MIP sensor exhibits high sensitivity with a LoD of (3 ± 1) × 10⁻¹² M, which is below the EU regulation limits for drinking water by six orders of magnitude, a linear range between 10 and 100pM, and an excellent selectivity. These results proved the effectiveness of template removal procedure by using a 70:30 MeOH:H₂O mixture and are a proof-of-concept for ultrasensitive and selective 2,4-D detection in real samples.