Sensor detects toxic herbicides.

Scientists at the Vietnam Academy of Science and Technology have successfully developed an advanced electrochemical sensor capable of detecting glyphosate herbicide residues at very low concentrations.

If herbicides are not managed and used properly, they will cause environmental pollution.

This result not only keeps pace with international research trends but also opens up practical applications in environmental monitoring and production safety assurance.

Glyphosate is one of the most widely used herbicides in the world since 1974. Due to the strong carbon-phosphorus bonds in its molecule, this compound is difficult to break down naturally, thus it can persist for a long time in soil and water. Many studies have shown that prolonged exposure to glyphosate can pose health risks to humans such as miscarriage, birth defects, or genetic mutations. Furthermore, when concentrations exceed permissible limits, glyphosate is toxic to aquatic organisms, polluting water sources and negatively impacting biodiversity. In this context, detecting and monitoring glyphosate residues in the environment has become a critical requirement for agricultural management and public health protection.

However, current analytical methods such as high-performance liquid chromatography (HPLC), gas chromatography (GC), or capillary electrophoresis, while offering high accuracy, require expensive equipment, complex sample processing procedures, and are difficult to implement on a large scale.

Based on this reality, a research team led by Associate Professor, Dr. Vu Thi Thu Ha has developed a new solution: an electrochemical sensor using an improved metal-organic framework (MOF) material, allowing for the rapid, accurate, and much lower-cost detection of trace amounts of glyphosate compared to traditional methods. This result was realized in a project funded by the Vietnam Academy of Science and Technology: "Fabrication of metal-organic framework (MOF) materials capable of effectively adsorbing glyphosate and application in the development of an electrochemical sensor for detecting trace amounts of glyphosate in the environment".

The electrochemical sensor is fabricated from two main materials: CuBTC and Zr-CuBTC. Zr-CuBTC is a metal-metal hybrid material chosen for its superior glyphosate capture ability. Replacing a portion of copper (Cu) with zirconium (Zr) expands the material's pore structure, facilitating glyphosate molecules' penetration and adsorption onto the sensor surface. Simultaneously, the new material significantly improves electrical conductivity, demonstrated by a sharp reduction in transmission resistance from 2,464 Ω (for CuBTC) to 703.3 Ω, indicating a marked improvement in conductivity.

Thanks to these improvements, the Zr-CuBTC sensor on the GCE electrode achieves a detection limit of just 9.0 × 10⁻¹³ M, sensitive enough to detect glyphosate at extremely low concentrations in water. Although some international studies have lower detection thresholds, the group's sensor still stands out due to its high overall performance, good stability, and applicability in real-world environmental conditions. Tests show that the device has a fast response time (only about 4.8 seconds), good repeatability, high selectivity, and is virtually unaffected by common compounds in water samples.

Building upon that foundation, the researchers continued to explore ways to overcome the inherent conductivity limitations of MOF materials by combining CuBTC with gold nanoparticles (AuPs). The integration of gold nanoparticles not only enhanced conductivity but also improved the electrocatalytic activity of the sensor. As a result, the team successfully developed a second version – a CuBTC/AuPs sensor – that produced a significantly stronger current signal, enabling the detection of glyphosate at very low concentrations (4.4 × 10⁻¹¹ M). The device also demonstrated high sensitivity, stable operation, and good repeatability under real-world measurement conditions.

Notably, the research did not stop at laboratory testing but was also validated on Red River water samples. Analysis results from the two types of sensors showed high similarity to the LCMS/MS method – a modern, highly accurate technique. This demonstrates that electrochemical sensors have the potential to become a reliable analytical tool, with clear advantages in cost, mobility, and deployment in environmental monitoring.

According to Associate Professor, Dr. Vu Thi Thu Ha, the research team improved the MOF material by integrating gold nanoparticles to enhance conductivity, thereby developing a highly sensitive electrochemical sensor capable of detecting glyphosate with high accuracy and a very low detection limit. The fabricated sensor can be stored for up to 24 hours in a dehumidified environment before use while maintaining stable measurement performance. Therefore, the device is suitable for direct field surveys, requiring no bulky equipment or highly specialized technicians.

With its low cost, simple operation, and immediate usability at the sampling site, this sensor facilitates easy application by local environmental officials, while also reducing the workload on environmental laboratories and agricultural control agencies. The deployment of this sensor for detecting glyphosate residue in the environment will become an effective tool, providing clear scientific evidence for regulatory agencies to strengthen control and enforce legal regulations. Building on these positive initial results, the research team hopes to further optimize the sensor to increase its durability, extend its shelf life, and better suit field conditions.

According to scientists from the Vietnam Academy of Science and Technology, the research results of the project have been published in many prestigious international scientific journals; not only contributing to solving the problem of monitoring pesticide residues in the environment, the electrochemical sensor for detecting glyphosate also demonstrates the ability of scientists at the Academy to master and develop advanced technology.

MINH HA

Source: https://nhandan.vn/cam-bien-phat-hien-thuoc-diet-co-doc-hai-post951676.html