This research addresses the development of electrochemical sensors for the determination of selected organic pollutants as an alternative to conventional analytical methods, which often require expensive equipment, trained personnel, time-consuming procedures, and substantial consumption of solvents and reagents. Three sensing systems were developed for the determination of electrochemically active neonicotinoids, electrochemically inactive neonicotinoids, and polystyrene nanoplastics.
The first sensor was developed for the determination of clothianidin, imidacloprid, and thiamethoxam using screen-printed three-electrode systems. The working electrode surface was modified through a simple, rapid, and repeatable electrochemical preconditioning procedure. The effects of different electrolytes and the selected electrochemical method were investigated during procedure optimisation. Electrochemical and surface characterisation confirmed an increase in the electrochemically active surface area, enhanced charge transfer, removal of surface contamination, and an increase in the abundance of oxygen-containing functional groups. Following optimisation of the measurement conditions, calibration curves and limits of detection were established using adsorptive differential pulse voltammetry. Sensor stability, preparation repeatability, and the effects of potential interferents were evaluated. The applicability of the sensor was assessed in surface water and honey samples.
The second sensor was designed for the determination of acetamiprid and thiacloprid using molecularly imprinted polymers as recognition elements. Synthesis conditions, monomer selection, and the ratios of analyte, monomer, and cross-linker were optimised. The polymers were characterised using scanning electron microscopy and infrared spectroscopy, while their binding properties were evaluated through adsorption and kinetic studies. The most suitable polymers were selected based on their imprinting factors, and their deposition onto a glassy carbon electrode was optimised. Calibration curves were established for both analytes, and the selectivity of the system was assessed.
The third sensor was developed for the determination of polystyrene nanoplastics. The gold working electrode of a screen-printed three-electrode system was modified with a thin mesoporous silica film and further functionalised with proline. The sensor was characterised using microscopic, spectroscopic, and electrochemical methods. Polystyrene particles of three sizes were investigated, and their properties were evaluated using dynamic light scattering, zeta potential measurements, and scanning electron microscopy. The potential and duration of particle accumulation on the sensor surface were optimised. Calibration curves were established using differential pulse voltammetry and electrochemical impedance spectroscopy. The highest sensitivity was achieved for the smallest particles, with sensitivity decreasing as particle size increased. The applicability of the sensor was also assessed in a bottled water sample.
The research data include the results of the preparation, optimisation, characterisation, and evaluation of the developed sensing systems and support the further development of electrochemical approaches for monitoring organic pollutants.
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