Capacitive sensor based on molecularly imprinted polymers for detection of the insecticide imidacloprid in water

This manuscript reports on the development of a capacitive sensor for the detection of imidacloprid (IMD) in water samples based on molecularly imprinted polymers (MIPs). MIPs used as recognition elements were synthesized via a photo-initiated emulsion polymerization. The particles were carefully washed using a methanol (MeOH) / acetic acid mixture to ensure complete template removal and were then dried. The average size of the obtained particles was less than 1 mu m. The imprinting factor (IF) for IMD was 6 and the selectivity factor (alpha) for acetamiprid, clothianidin, thiacloprid and thiamethoxam were 14.8, 6.8, 7.1 and 8.2, respectively. The particles were immobilized on the surface of a gold electrode by electropolymerization. The immobilized electrode could be spontaneously regenerated using a mixture of MeOH/10 mM of phosphate buffer (pH = 7.2)/triethylamine before each measurement and could be reused for 32 times. This is the first-time that automated regeneration was introduced as part of a sensing platform for IMD detection. The developed sensor was validated by the analysis of artificially spiked water samples. Under the optimal conditions, the linearity was in the range of 5-100 mu M, with a limit of detection (LOD) of 4.61 mu M

The geology of the Naran area, Donegal, Ireland.

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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