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

Abstract

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 µm. The imprinting factor (IF) for IMD was 6 and the selectivity factor (α) 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 µM, with a limit of detection (LOD) of 4.61 µM. Nowadays, neonicotinoids (neonics) are the most important class of pesticides in the global market. Their "success" story started in 1991 by introducing imidacloprid (IMD) on the market. Since then, for many years IMD has become the world's largest selling pesticide with the registered uses for over 140 crops in 120 countries 1,2. It is extensively used at a large scale with applications ranging from plant protection, veterinary products, and seed coating. As a result of its extensive usage, IMD can be found as a pollutant in all environmental compartments (soil, water and air) 3. Neonics act by binding to the nicotinic acetylcholine receptors (nAChRs) in their target invertebrates. They mimic the action of neurotransmitters, leading to the continuous stimulation of neurons. In doing so, they could cause the death of their target invertebrates 3. Neonics are highly water soluble, persistent in water, soil, minimally degraded by light and not volatile, which make them easily transported from an area of application to different environmental compartments 4. In addition to that, it was found that like other pesticides they have a negative impact on non-target organisms. IMD and other members of the first generation are highly toxic to bees 5,6. These chemical properties in addition to their negative environmental impacts have raised EU concern 7. Pesticides in general could easily contaminate supplies of drinking water via surface or ground water systems. Depending on the quantity and toxicity level of a pesticide together with the frequency of exposure to the contaminated drinking water, pesticides in water could negatively affect human health and environment. It was found that neonics could have lethal and sublethal effects on many aquatic invertebrates. The acute and chronic neonics t...

Molecularly Imprinted Polyscopoletin for the Electrochemical Detection of the Chronic Disease Marker Lysozyme

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