A Simple Paper Chromatography Experiment with Multiple Learning Outcomes for the Undergraduate Curriculum

This work discusses a simple and inexpensive paper chromatography experiment to separate 1,10-phenanthroline and salicylic acid from a sample mixture. Aqueous Fe2+ and Fe3+ solutions were used to form orange and violet colored spots with 1,10-phenanthroline and salicylic acid, respectively. The appearance of distinct colored spots on the cellulose paper provides each student a clear visual method for analyte identification. This experiment teaches several concepts including the principle of chromatography, the selective formation of colored complexes between Fe2+ and Fe3+ ions and analytes, and the concepts of the color wheel and complementary colors. This experiment gives a deeper understanding of the structure of the iron complexes that are formed, teaches students how to calculate the Rf values, and helps students understand the relationship between pKa values and the relative polarity of compounds. The visual clarity of the results and the simplicity of this experiment make it an interesting approach for introducing chromatographic techniques in chemistry education to undergraduate students.