Sensors enable rapid detection of harmful herbicides
Glyphosate has been one of the most widely used herbicides worldwide since 1974. With a highly stable carbon–phosphorus bond in its molecule, it is difficult to degrade naturally, meaning it can persist for long periods in soil and water. Numerous studies have shown that prolonged exposure to glyphosate may harm human health, causing miscarriage, birth defects, and genetic mutations. In addition, when concentrations exceed permissible limits, glyphosate can be toxic to aquatic animals, pollute water sources, and affect biodiversity.
Detecting and monitoring glyphosate residues in the environment has therefore become an urgent priority in agricultural management and public health protection. However, current methods such as high-performance liquid chromatography (HPLC), gas chromatography (GC), or capillary electrophoresis, though highly accurate, require sophisticated equipment and complex sample processing procedures, making them difficult to apply widely.
To address this challenge, a research team led by Assoc Prof Dr Vu Thi Thu Ha has successfully developed a new solution: an electrochemical sensor using modified metal-organic framework (MOF) materials, capable of detecting trace amounts of glyphosate quickly, accurately, and at much lower cost than traditional methods. This is the outcome of a project under the Vietnam Academy of Science and Technology entitled: “Fabrication of MOF materials with efficient adsorption of Gly and their use in the development of electrochemical sensors for trace detection of Gly in the environment” (code: VAST07.05/23-24).
Material innovation – enhancing performance
The electrochemical sensor is fabricated from two main materials: CuBTC and Zr-CuBTC. Zr-CuBTC, a combination of two metals, was chosen for its superior ability to “capture” glyphosate. Partial replacement of copper (Cu) with zirconium (Zr) enlarged the pore structure, allowing glyphosate molecules to penetrate and attach more easily to the sensor surface. Notably, the new material also markedly improved electrical conductivity, with resistance reduced from 2,464 Ω (CuBTC) to only 703.3 Ω.
The Zr-CuBTC sensor on a GCE electrode achieved a detection limit as low as 9.0 × 10⁻¹³ M, sensitive enough to detect glyphosate at extremely low concentrations in water. Although some international studies have reported lower detection thresholds, the new sensor stands out for its overall efficiency, stability, and applicability in real-world environments. Tests showed rapid response time (just 4.8 seconds), good repeatability, high selectivity, and no interference from other common compounds in water samples.
Diagram of the modification process and working principle of the sensor with integrated gold nanoparticles
To overcome the low conductivity of MOF materials, the researchers integrated CuBTC with gold nanoparticles (AuPs). This combination not only enhanced conductivity but also improved the sensor’s electrochemical catalytic activity. As a result, the team successfully developed a second version – the CuBTC/AuPs sensor – which produced a much stronger current signal, enabling detection of glyphosate at very low concentrations (down to 4.4 × 10⁻¹¹ M).
According to Assoc Prof Dr Vu Thi Thu Ha, this detection limit is not only much lower than that of several previously published electrochemical sensors (typically 10⁻⁹–10⁻⁸ M) but also approaches the performance of advanced systems reported in leading international journals. The device also demonstrated stable operation, high sensitivity, and consistent results under real measurement conditions.
(A) Scanning electron microscopy (SEM) image of the material; (B) image showing the uniform distribution of gold nanoparticles in the sensor
One notable feature of the study is its strong practical potential. Both types of sensors were tested directly on samples from the Red River, producing results consistent with LC-MS/MS analysis (a highly accurate modern method). This proves that electrochemical sensors can become a reliable alternative tool, with clear advantages in cost and portability.
Assoc Prof Dr Vu Thi Thu Ha noted that the team had improved MOF materials by integrating them with gold nanoparticles to increase conductivity, creating an ultra-sensitive electrochemical sensor capable of detecting glyphosate with high accuracy and very low detection limits. The sensor can be preserved for up to 24 hours under desiccated conditions before use while maintaining performance, making it suitable for on-site surveys without bulky equipment or specialised technicians. Thanks to its low cost, simple operation, and immediate usability at sampling sites, the device can be easily applied by local environmental officers, reducing the burden on environmental laboratories and agricultural control units.
The project results have been published in prestigious international journals indexed in SCIE and Scopus. In 2024, the team successfully developed the ultra-sensitive glyphosate sensor and published it in Analytical Letters. In the same year, research on the gold nanoparticle-integrated sensor was published in the Vietnam Journal of Chemistry, opening up new applications in water quality monitoring.
The electrochemical sensor developed by the team not only helps address the issue of pesticide residues but also demonstrates the capacity of Vietnamese scientists to master advanced technology. Although glyphosate was officially banned from the list of approved pesticides in Vietnam under Decision No. 1186/QD-BNN-BVTV (10 April 2019), due to its strong effectiveness, it continues to be illegally used in many localities. Therefore, deploying this sensor to detect glyphosate residues in the environment will provide powerful scientific evidence, helping authorities tighten control and enforce regulations effectively.
Building on these initial positive results, the research team aims to further optimise the sensor to improve durability, extend storage life, and better suit field conditions. At the same time, expanding the MOF material platform and sensor technology to other pollutants such as insecticides, heavy metals, or trace substances from waste is also a key direction for future research.
Translated by Phuong Huyen
Link to Vietnamese version
