The goal of achieving food safety and quality has become increasingly important in relevant areas. The achievement of this objective includes a significant effort in different areas related to the production of raw materials, storage, transportation, etc. One of the central areas in the verification of food safety and food quality control is related to the analysis of food components and, in particular, possible toxic substances that they may contain. Therefore, the demand for appropriate methods for the determination of these substances is increasingly demanding. Thus, not only is accuracy and precision sought in the results of the analysis, but also the speed, simplicity and lowering of costs. In this way, electrochemical techniques and, particularly, electrochemical biosensors have emerged in recent times as good candidates to satisfy such requirements. This review summarizes the advances made in research and development centers located in South American countries related to the development of electrochemical biosensors for the determination of toxic substances present in foods, particularly mycotoxins and herbicides.

Electrochemical sensors and biosensors are analytical tools, which are in continuous development with the aim of generating new analytical devices which are more reliable, cheaper, faster, sensitive, selective, and robust than others. In matrices related to agroalimentary, environmental, or health systems, natural or synthetic compounds occur which fulfil specific roles; some of them (such as mycotoxins or herbicides) may possess harmful properties, and others (such as antioxidants) beneficial ones. This imposes a challenge to develop new tools and analytical methodologies for their detection and quantification. This review summarises different aspects related to the development of electrochemical sensors and biosensors carried out in Argentina in the last ten years for application in agroalimentary, environmental, and health fields. The discussion focuses on the construction and development of electroanalytical methodologies for the determination of mycotoxins, herbicides, and natural and synthetic antioxidants. Studies based on the use of different electrode materials modified with micro/nanostructures, functional groups, and biomolecules, complemented by the use of chemometric tools, are explored. Results of the latest reports from research groups in Argentina are presented. The main goals are highlighted.

The optimization of the synthesis of CdS nanocrystals (CdS NCs) stabilized with 3-mercaptopropionic (MPA) acid was studied using chemometric tools. All factors (variables) involved in the CdS NC synthesis were optimized. The analysed factors were the CdCl₂, Na₂S and 3-mercaptiopropionic acid concentrations, and the time and temperature of the reaction. First, a full factorial design was carried out to evaluate the effect of all factors and their interactions, where the analysed factors were the CdCl₂, Na₂S and 3-mecaptiopropionic acid concentrations, and the time and temperature of the reaction. Second, a central composite design was chosen for optimization of the factors. The optimization of the CdS NC synthesis was carried out using the fluorescence intensity of CdS NCs. The values of the factors that maximize the fluorescence intensity of the synthetized CdS NCs were a concentration range of CdCl₂, Na₂S and MPA of (7.96–8.49) × 10⁻³ mol L⁻¹, (6.06–8.50) × 10⁻³ mol L⁻¹ and (47.58–71.85) × 10⁻³ mol L⁻¹, respectively, and a temperature range of (20–74) °C. Under the best conditions, the relative error was 14%. The optimized CdS NCs were purified through size selective precipitation. A fluorescence quantum yield (QY) of 1.02% was obtained. On the other hand, the bulk band gap of the CdS NCs was 2.99 eV (close to 415 nm). The synthesis of the NCs studied was reproducible and they had good fluorescence.