Classroom-Friendly HPLC Experiments for Multidimensional Learning: Assay of Acetaminophen Using Propylene Glycol as a Green and Safe Mobile Phase

This study presents the development and implementation of classroom-friendly high-performance liquid chromatography (HPLC) experiments that integrate analytical chemistry principles with green chemistry and real-world applications. The approach is based on a novel method originally developed for pharmaceutical manufacturing, employing propylene glycol (PG) as a low-toxicity, environmentally benign mobile phase for the assay of acetaminophen (AC) and caffeine (CF) tablets. The procedure was adapted for instructional use and extended to incorporate the environmental analysis of laboratory wastewater alongside drug quality control. With PG’s low-hazard profile, students can safely perform HPLC operations while gaining a concrete understanding of green solvent selection in sustainable analytical practice. In addition, the method enables rapid analysis─approximately 2 min per run─making it well-suited for time-limited sessions. The activity is organized into four sections: (1) mobile phase preparation and instrument setup, (2) AC tablet assay with external and internal standard calibration, as well as single- and multipoint calibration approaches, (3) laboratory waste treatment followed by HPLC analysis, and (4) preliminary greenness assessment. This modular design allows flexible adaptation to various learning objectives and schedules. Postlaboratory surveys indicated strong student achievement in conceptual understanding, quantitative data analysis, sustainability awareness, and perceived professional relevance. By authentically combining chemical analysis with safety-conscious design, this work offers a practical model for embedding green chemistry into instrumental analysis curricula, fostering both technical competence and a sustainability-oriented mindset essential for modern scientific practice.