PROJECT-BASED LEARNING: PURIFICATION AND CHARACTERIZATION OF 2,4-D, LINKING CHEMISTRY AND PLANT TISSUE CULTURE

Project-Based Learning (PjBL) offers a student centered framework that integrates theoretical knowledge with hands on experimentation, fostering autonomy, collaboration, and critical thinking. This approach is particularly meaningful in experimental sciences such as chemistry, where laboratory practice is essential. In this work, biochemistry students developed a PjBL project focused on the isolation, characterization, and biological evaluation of 2,4-dichlorophenoxyacetic acid (2,4-D), a widely used synthetic auxin. Students extracted 2,4-D from a commercial dimethylamine salt formulation through acid precipitation, filtration, and recrystallization. Characterization methods, including melting-point analysis and IR spectroscopy, confirmed the identity and purity of the compound. Although the yield reached only 57.66%, it demonstrated the feasibility of obtaining usable reagent-grade material from low cost sources. To assess biological activity, purified 2,4-D was applied to in vitro cultures of Lupinus mutabilis, an Andean legume with significant nutritional and agronomic value. Callus induction varied with hormone concentration, no response occurred in the control, while the highest concentration (6 mg L⁻¹) produced compact, rapidly growing callus, confirming the functional integrity of the purified compound. These results align with known auxin-dependent patterns of dedifferentiation in legumes. Overall, this PjBL work strengthened students’ practical competencies, problem solving abilities, and scientific reasoning.