Case Studies on Sample Preparation with Diluted Acid for Elemental Determination

Abstract

Green chemistry provides a framework for redesigning laboratory practices to reduce environmental and safety impacts. In elemental analysis, replacing highly concentrated acids during sample preparation represents an important step toward more-sustainable practices. This study evaluates three didactic case studies based on the use of diluted nitric acid for sediment preparation in analytical and environmental chemistry courses. The participants included secondary technical students in biotechnology (n = 5) and undergraduate chemistry students (n = 43) from the analytical and environmental chemistry course, who were encouraged to critically evaluate conventional procedures that employ concentrated acids. Before classroom implementation, the alternative protocol based on diluted nitric acid was examined to ensure its analytical feasibility. Data were collected through questionnaires, responses completed by students in a structured monitoring form during the activities. The students proposed new alternatives and different approaches to solving problems related to chemical activities. The results demonstrated that this approach enabled students to integrate new knowledge in a critical, creative, and collaborative manner. Furthermore, the didactic strategy provided favorable conditions and essential experiences for training future chemical professionals who are aware of and reflective of their actions.