Separação dos pigmentos extraídos da espécie amazônica Bixa Orellana L. (urucum) por cromatografia em camada delgada, para estimular o ensino-aprendizagem de química orgânica

Abstract

The research was developed based on the problem “Can the separation of natural pigments extracted from the Amazonian species, Bixa orellana (annatto), through thin layer chromatography stimulate teaching-learning in a 3rd year high school class?”. The central objective of the study was to stimulate the teaching and learning of chemistry, through the separation of natural pigments extracted from the Amazonian species Bixa orellana L., popularly known as annatto, using the thin layer chromatography technique. Therefore, to develop the research, the pigments were initially extracted from the seeds of the fruits of the selected species by maceration with ethanol. After eliminating the solvent, the obtained extract was subjected to separation by column chromatography, which used silica gel as the stationary phase and mixtures of hexane and ethyl acetate as the mobile phase, obtaining 20 fractions. Of these 20 fractions, 9 were selected to develop the class proposal, as they were the ones that presented pigments with the greatest difference in tone. The research was carried out at the Deusolina Salles Farias State School in a third-year high school class. The proposal consisted of two interventions, each containing two classes. The first intervention consisted of holding a theoretical class, to explain the syllabus of intermolecular forces, polarity and chromatographic method; The second consisted of the application of an experimental practice, where thin layer chromatography was used to separate pigments extracted from the Amazonian species Bixa orellana. The research had a qualitative approach and semi-structured questionnaires were used as a data collection instrument. From the research results, it was observed that the students managed to increase their level of knowledge about the contents that were covered in the classroom, and they felt motivated by carrying out the experimental class.