Molecularly imprinted polymer based capacitive sensing of a specific Leuckart marker 4-methyl-5-phenylpyrimidine in wastewater

In this paper, a capacitive sensor based on molecularly imprinted polymers (MIPs) was developed for monitoring of 4-methyl-5-phenyl pyrimidine (4M5PP), a route-specific by-product in the Leuckart preparation of amphetamine, in wastewater. MIPs were computationally designed and synthesized via a photo-initiated emulsion polymerization with use of methacrylic acid (MAA), 2- vinylpyridine (2-VP) as functional monomers and ethylene glycol dimethacrylate (EGDMA) as a cross-linker. The obtained particles were of spherical shape with average size of around 1 mu m as seen in scanning electron microscopy (SEM) and measured by dynamic light scattering (DLS). Since the Leuckart reaction takes place at elevated temperatures, the thermal stability of the obtained polymer particles was tested, and it was confirmed that they are stable within a wide temperature range. After the characterization, the polymer particles were electro-immobilized on gold electrode transducers. The response of the sensor showed a linear dependence on the concentration of 4M5PP from 100 mu M to 3000 mu M, with a detection limit of 80 mu M (S/N = 3). The developed 4M5PP-MIPs-based sensor offers the advantage of spontaneous regeneration and re-using of a single electrode up to 24 times with a maintained signal intensity response of more than 90 %. When used for the detection of 4M5PP in wastewater samples, the recovery of the sensor to the sample was 95-101 %, with the RSD of 1.49-4.64 %. To the best of our knowledge this manuscript is the first to describe both the MIPs towards 4M5PP and its electrochemical detection