Pesticides such as herbicides and insecticides are widely used for protecting crops and forests against weeds, insects, and pests. Fenitrothion, trifluralin and glyphosate are preferred due to their cost-effective, high efficiency and broad-spectrum nature. Unfortunately, pesticides are toxic and harmful thus their increasing use has posed a great threat to human health and environment safety considering that the crops only consume up to 1% of the applied pesticides while the rest get leached into the soil and underground water. Therefore, researchers have been looking for effective methods for their detection and analysis.
Currently, most of the conventional methods used for pesticide analysis like enzyme biosensors, electrochemical technique, and gas-chromatography-mass spectroscopy are only applicable in laboratories due to their expensive and time-consuming nature. To the end, today’s researchers have been focusing on the development of effective tools for toxic pesticide analysis and detection.
Micro-and mesoporous polymers which can be synthesized through polymeric reactions of multifunctional monomers have attracted significant interests amongst researchers. The polymer materials exhibit unique properties like heterogeneous catalysis, ultralow density and high gas storage capable of achieving the desired intriguing functions. However, to date, the use of fluorescence micro-and mesoporous organic polymers in detecting and analysis of toxic pesticides have not been explored.
A group of researchers at the Dalian University of Technology: Biao Zhang (PhD student), Jun Yan (PhD student), Yingqi Shang (PhD student), and Professor Zhonggang Wang synthesized fluorescent organic micro-and mesoporous polyaminals for detection of toxic pesticides. It comprised of pendant dibromotriphenylamine and triphenylamine chromophore groups. The authors investigated the chemosensing properties of the synthesized polymers by considering their porosity and chemical structures in conjunction with analytes like fenitrothion, trifluralin and glyphosate as well as the effects of different solvents and acid-based conditions. Various techniques including element analysis were used to characterize the chemical and porous structures. Their research work is currently published in the research journal, Macromolecules.
The authors observed a BET surface area of up to 507 m2g-1 and pore sizes in the range of 0.5-36.2 nm in the resultant polymers. Thus, they exhibited excellent chemosensing properties towards toxic pesticides, especially at low concentrations. For instance, a fluorescent fabricated test paper turned dark immediately upon coming in contact with the pesticide solution. Moreover, the quenching degree remained nearly constant after repeatedly using for 10 times. Also, the authors discovered that the pore size of the polymers affected their sensitivity to pesticides. The broader the pore size of a polymer, the more sensitive it was. This was attributed to the mass transfer of the pesticides molecules that was facilitated by broader pore sizes.
Dalian University of Technology researchers for the first time successfully demonstrated the use of fluorescent porous polymers for sensing toxic pesticides. Its use comes with numerous advantages with regard to sensitivity, portability, and rapidity. Furthermore, they are inexpensive to use since they can be recovered and reused without losing their sensitivity. Therefore, fluorescent porous polyaminals become promising candidates for detection and analysis of toxic pesticides.
Zhang, B., Yan, J., Shang, Y., & Wang, Z. (2018). Synthesis of Fluorescent Micro- and Mesoporous Polyaminals for Detection of Toxic Pesticides. Macromolecules, 51(5), 1769-1776.Go To Macromolecules