A team of researchers from universities in Scotland, Portugal and Germany has developed a sensor that can help detect the presence of pesticides in very low concentrations in water samples.
Their work, described in a new paper published today in the journal Polymer Materials and Engineering, could make water monitoring faster, easier, and cheaper.
Pesticides are widely used in agriculture around the world to prevent crop losses. However, caution must be exercised, as even small leaks into soil, groundwater or seawater can cause harm to human, animal and environmental health.
Regular environmental monitoring is essential to minimize water contamination so that prompt action can be taken when pesticides are detected in water samples. Currently, pesticide testing is usually done under laboratory conditions using methods such as chromatography and mass spectrometry.
While these tests provide reliable and accurate results, they can be time-consuming and expensive to perform. One promising alternative is a chemical analysis tool called surface-enhanced Raman Scattering (SERS).
When light hits a molecule, it scatters at different frequencies depending on the molecular structure of the molecule. SERS allows scientists to detect and identify the amount of residual molecules in a test sample adsorbed on a metal surface by analyzing the unique “fingerprint” of light scattered by the molecules.
This effect can be enhanced by modifying the metal surface so that it can adsorb molecules, thereby improving the sensor’s ability to detect low concentrations of molecules in the sample.
The research team set out to develop a new, more portable test method that could adsorb molecules into water samples using available 3D printed materials and provide accurate initial results in the field.
To do so, they studied several different types of cell structures made from a mixture of polypropylene and multi-walled carbon nanotubes. The buildings were created using molten filaments, a common type of 3D printing.
Using traditional wet chemistry techniques, silver and gold nanoparticles are deposited on the surface of the cell structure to enable a surface-enhanced Raman scattering process.
They tested the ability of several different 3D printed cell material structures to absorb and adsorb molecules of the organic dye methylene blue, and then analyzed them using a portable Raman spectrometer.
The materials that performed best in the initial tests – lattice designs (periodic cellular structures) bound to silver nanoparticles – were then added to the test strip. Small amounts of real insecticides (Siram and paraquat) were added to seawater and fresh water samples and placed on test strips for SERS analysis.
The water is taken from the mouth of the river in Aveiro, Portugal, and from taps in the same area, which are regularly tested to effectively monitor water pollution.
The researchers found that the strips were able to detect two pesticide molecules in concentrations as low as 1 micromole, which is equivalent to one pesticide molecule per million water molecules.
Professor Shanmugam Kumar, from the James Watt School of Engineering at the University of Glasgow, is one of the authors of the paper. This work builds on his research into the use of 3D printing technology to create nanoengineered structural lattices with unique properties.
“The results of this preliminary study are very encouraging and show that these low-cost materials can be used to produce sensors for SERS to detect pesticides, even at very low concentrations.”
Dr. Sara Fateixa from the CICECO Aveiro Materials Institute at the University of Aveiro, a co-author of the paper, has developed plasma nanoparticles that support SERS technology. While this paper examines the system’s ability to detect specific types of water contaminants, the technology could easily be applied to monitor the presence of water contaminants.
Post time: Jan-24-2024