In its latest edition, the Induambiente Magazine highlights the research carried out by researchers from the Center for Nanoscience and Nanotechnology (CEDENNA) and the Institute for Agricultural Research (INIA) to measure agrochemical residues in fresh fruits and vegetables, more quickly and at a lower cost than conventional laboratory techniques. With this, monitoring could be extended to small and medium-sized farmers, helping to deliver less contaminated agricultural products to the population.
This is a project of special importance, considering that, according to data from the Chilean Agency for Food Safety and Quality (ACHIPIA), during the years 2019 and 2020 the category of these foods accumulated the largest number of alerts, all corresponding to hazards. chemicals specifically associated with pesticide residues.
A convenient innovation, the details of which the publication reviews in detail.
Analysis by Chromatography
Currently in Chile, the maximum limit of pesticide residues that can exist in agricultural products is regulated by Exempt Resolution 892 of the Ministry of Health, published in November 2020, which establishes the admissible values for the different pesticide-food combinations.
Measurements to control compliance with said regulations are carried out through laboratory techniques based on chromatography, a method that "can be understood as a process of separating components from a complex mixture for their subsequent identification and quantification". This is explained by Dr. Rafael Melo, a researcher who works at the Pesticide Residue and Environment Laboratory of the Regional Research Center - INIA La Platina, one of the few accredited by the National Institute for Standardization to carry out these analyzes in Chile. This center has various chromatographic techniques that allow it to detect approximately 200 pesticides in different matrices, such as soil, water and vegetables (fruits and vegetables), and indicate the concentration of these pollutants.
"Chromatography is the international gold standard for analyzing pesticides and determining the amount of residues of these compounds that may be present in different matrices. It is a robust technique that provides reliable results," underlines the INIA professional.
Nanoparticles as Sensors
Beyond what has been stated, developing new solutions that can facilitate the detection of agrochemicals in food is extremely important. In this sense, INIA and CEDENNA are working on a project that "seeks to evaluate the use of nanoparticles, materials in a size range between 1 and 100 nanometers, for the detection of pesticides in vegetables", explains Dr. Rafael Melo. He adds that, based on this, they intend to generate a methodology that delivers results quickly and at a lower cost compared to the techniques currently available, and allows small and medium-sized farmers to also access these analyses.
"All the nanoparticles used in the project were produced within the Institute's premises, and each one is now being characterized to investigate their optical, structural and morphological properties, and use them as sensors for different pesticides", the INIA researcher notes.
The specialist adds that the main technical challenge is to design nanomaterials that can respond to different agrochemicals in a unique way, delivering a rapid detection signal.
A relevant advantage that nanoparticle sensors would have is that they would be cheaper than chromatography: "For now, as we still have the methodology under development, it is difficult to accurately estimate an approximate cost, but it can be said that the technology will cost less ", says Dr. Melo. He reiterates that the central idea is to make it accessible to small and medium-sized farmers.
The INIA researcher, who works in collaboration with CEDENNA, comments that after completing the current stage of synthesis and characterization of the nanomaterials to be used, the pesticide detection tests will begin, using lettuce as a test matrix, since it is a vegetable that is ready to consume once it is harvested, so it is very necessary to monitor the agrochemical residues they contain, in order to protect consumers. "At first we are going to focus on five different pesticides, but in the future we want to expand it much more," he says.
After that, the project will focus on validating the detection and quantification method in the laboratory, to offer it to the agricultural sector at a lower cost than current options. In the medium and long term, it is intended to take these sensors to the field to carry out the analyzes in situ and thus further shorten the delivery time of the results.
It is also expected to disseminate the project to highlight the problem of pesticide residues in food and show the benefits that the use of nanotechnology can deliver to agriculture.
Rafael Melo points out that, in addition to the aforementioned project, INIA has also focused on "early stages of the production chain to ensure that the levels of pesticide residues do not exceed the levels legally tolerated and specified in Resolution 892 Exempt from the Ministry of Health, which is a regulation quite in line with international guidelines". This preventive approach aims to increase the quality and safety of agricultural products, guaranteeing the safety of the food that reaches the consumer's table.
In this context, they are applying to different research projects whose objectives are to provide a tool that allows ensuring "in situ" the adequate levels of use of pesticides, according to the label, and to optimize their application in the field through precision and dosage instruments. . "If pesticides are used under the legally tolerated limits, they can be prevented from having a negative impact on people and the environment. Today, if a farmer wants to make sure that the concentration he is applying is adequate, he has to take a sample and send it to a laboratory that will take 24 or 48 hours to analyze, a time that many times the producer is not willing to wait for, on the other hand, with a tool that can be used in situ and delivers immediate results, actions can be taken corrective measures in real time and prevent an error early in the application chain from propagating," he says.
The Contribution of CEDENNA
The Center for Nanoscience and Nanotechnology (CEDENNA) is the largest center in the country in the area, of an inter-university and multidisciplinary nature, with facilities at the University of Santiago. As such, it has provided important support for the advancement of the mentioned projects and also in other environmental initiatives.
This is how its director, Dr. Dora Altbir, National Prize for Exact Sciences 2019, explains it: "CEDENNA is a research center whose fundamental purpose is to develop frontier knowledge in nanoscience and transform it into innovative, reliable and safe solutions to environmental problems. environment, agro-industry, mining, energy, among others. We have extensive experience in the use of nanomaterials and we have specialized teams to have an impact in various areas."
In relation to the project that they are developing with INIA, he points out that the objective is "to contribute to the control of the risk represented by pesticide residues in products intended for human consumption, complying with food safety regulations, an issue that is a reason permanent source of analysis and concern for national agriculture and, by the way, for those who export to international markets".
He adds that, according to plans, the first results of this initiative should be delivered during the next year and it is expected to have a validated prototype by the end of 2024.
Regarding its scope and projections, Dr. Dora Altbir comments: "Currently, agricultural producers are faced with a very diverse battery of alternatives to try to meet the demanding national and international standards. With the proposed pesticide sensor, after harvesting your product, you must take a sample to a laboratory that in the future has this technique, where an extract of the harvest will be obtained to submit it to a rapid analysis process to detect, through the nanoparticles, the concentration of pesticide that it has the food. This is key to determine if the maximum residue limit (MRL) of pesticides established by Exempt Resolution 892 of the Ministry of Health is met. This is essential for both the internal and external markets, compared to current regulations on MRLs that were developed according to the latest regulations of the Codex Alimentarius, of the European Union, and the Food and Drug Administration ( FDA)".
Other environmental areas that CEDENNA has focused on are the remediation of water and soil from various contaminants, "an area in which nanotechnology has emerged as the most efficient solution. We have also addressed the use of lower amounts of pesticides, fungicides and fertilizers ; renewable energies and others", says the director of the research center.
It also highlights that they have the only nanosafety laboratory in the country, whose members represent Chile before the Organization for Economic Cooperation and Development (OECD) on these issues. This laboratory works with state-of-the-art equipment, such as the Elpi + (Electrical Low Pressure Impactor), a highly specialized instrument –unique in South America– that "allows the detection of atmospheric aerosols and nanoparticulate material in the air, thus contributing to preventing pollution in workers exposed to nanoparticles in different industries, as well as scientists and researchers themselves.
*A nanometer is equal to 1x10-9 meters. This relationship could be graphed with the difference in size that exists between an apple and the globe.
*A platform called Open Lab CEDENNA created this research center so that companies can access the advanced solutions and technical advice they develop. Those interested can be contacted through the website www.cedenna.cl
Article published in InduAmbiente 179 (November-December 2022), pages 68 to 71.