People are afraid of pesticide residues when buying vegetables, and they are afraid of pesticide residues when eating fruits... People often "talk about the discoloration of pesticides."
Recently, Jiang Changlong, a researcher at the Institute of Solid State Physics, Hefei Institute of Physical Sciences, Chinese Academy of Sciences, and his team developed a new, enzyme-free portable sensing platform (hereinafter referred to as the sensing platform), which can detect in the environment and food within 2 seconds. Glyphosate residue, final concentration results are displayed directly on the smartphone. Relevant research results were published in the Journal of Hazardous Substances.
"See" the result in 2 seconds on site
Research team members use test paper to detect glyphosate on site. Picture provided by the research team
"People only need to wet the surface of fruits and vegetables, and gently wipe the surface with the test paper, after about 2 seconds , use ultraviolet lamp to illuminate, and you can roughly judge the level of glyphosate residual concentration through the color change of the test paper," Jiang Changlong told reporters.
If the test paper is blue, it means the residual concentration of glyphosate is very low; when the test paper is pink, it means the concentration is high; when the test paper turns orange-red, it means the concentration is very high.
"This method is a preliminary screening and is suitable for people to self-test at home." Jiang Changlong said that if you want to get more accurate results, you need to put the test paper into the test paper slot of the sensing platform. The sensor platform is illuminated by the built-in UV lamp, and then a photo of the test paper is taken with a mobile phone. The mobile phone's color recognition software is used to automatically analyze and convert the result, showing whether the final pesticide residue concentration result exceeds the standard or does not exceed the standard.
Jiang Changlong introduced that the sensing platform includes sensors, smartphones that can be used to read data, and mobile phone accessories that provide fluorescence detection of environments. "The sensor is the main 'contributor'. It is composed of blue carbon dots and gold nano- clusters designed and prepared by the team. It can quickly 'identify and detect glyphosate'."
The principle is that when glyphosate is added to the sensor, it The carbon dot reaction causes the blue fluorescence of the carbon dots to be rapidly quenched, while the orange fluorescence of the gold nanoclusters remains unchanged. Visually, the fluorescence color of the test paper changes from blue to pink and finally to orange-red. The
team tested some actual samples, such as fruits, vegetables and water samples stained with glyphosate residues, and the test results were basically consistent with the laboratory test results.
Jiang Changlong said that the sensor developed by his team is faster and more convenient, can be operated by people without professional training, and can achieve on-site or real-time detection that cannot be achieved by laboratory testing. It is suitable for grassroots environmental supervision departments, farmers' markets and supermarkets. , individual consumers.
"Pesticide residue" does not mean "pesticide residue exceeds the standard"
Ratio fluorescence sensor for rapid visual and quantitative detection of glyphosate residue schematic diagram provided by the research group
Glyphosate is currently the most widely used herbicide in the world. Among organophosphorus pesticides occupies an important position in. “This is also an important reason why the team chose glyphosate for pesticide residue testing.” Jiang Changlong said.
Glyphosate is absorbed through the stems and leaves and then transmitted to all parts of the plant, inhibiting enolpyruvyl shikimate phosphate synthase in the plant, thereby inhibiting the transfer of shikidomin to phenylalanine , tyrosine and color The conversion of amino acids interferes with protein synthesis, leading to plant death.
However, higher usage and unreasonable usage methods will cause glyphosate residues in agricultural products to exceed the standard.
With the improvement of living standards, people's environmental awareness and safety awareness are increasing day by day. Jiang Changlong said, "Currently, people usually use laboratory instruments or enzyme inhibition methods to detect pesticide residues, but this detection is mostly done by professionals, the detection equipment is expensive, and the test results take two to three days to come out."
Therefore, The development of fast, effective, on-site detection methods for glyphosate residues has become a key link in controlling and treating organophosphorus pesticide residue pollution and hazards.
"It should be pointed out that pesticide residue does not mean that pesticide residue exceeds the standard. According to the pesticide residue limit, China has proposed a maximum limit of glyphosate residue of 4.14 micromoles." Jiang Changlong said that if the pesticide residue does not exceed the maximum limit, it is It is safe and people can eat it with confidence.
In addition, it is worth noting that as fruits, vegetables and other agricultural products account for an increasing proportion of my country's diet, their quality and safety have attracted much attention, and residue limit standards are also being revised in a "scientific and rigorous" direction.
Constructing a rapid detection platform for multiple target analytes
Monitoring platform based on smartphones Visual quantitative detection of glyphosate Photo courtesy of the research group
"This article reports a rapid visual fluorescence sensing platform for quantitative detection of glyphosate. The The innovation of the method is that it is combined with a smartphone to process the fluorescence signal, which is convenient and accurate. In addition, the sensing system uses two fluorescent substances as signals instead of relying on enzymes, which has certain application potential in on-site detection." A reviewer said so.
However, Jiang Changlong admitted frankly that the sensor developed this time is only for the detection of glyphosate residues. "Currently, the team is exploring and developing rapid detection methods and devices for other types of pesticides, such as pyrethroids, carbamates, etc."
Furthermore, the sensor's detection signal relies on changes in broad-spectrum fluorescence chromaticity, which may be affected by the use of ambient light.
Jiang Changlong said, "We hope to further upgrade the accessories of the detection platform, or develop other detection methods and build sensors to avoid any adverse interference from external factors on the detection results."
In the next step, the research team will focus on exploring multi-color luminescence The preparation of nanoprobes further builds a rapid detection platform for a variety of target analytes, and establishes an evaluation system and technical standards based on nanometer light effect sensing devices for the detection of various pollutants in the environment. It is expected to be used in visual analysis of human health early warning. New progress has been made in testing.
related paper information:
https://doi.org/10.1016/j.jhazmat.2022.129320
Source: Chinese Science Journal
Editor: Jiang Jiang Typesetting: Xiaotong
