Egg-Citing! Isolation of Protoporphyrin IX from Brown Eggshells and Its Detection by Optical Spectroscopy and Chemiluminescence

A simple and cost-effective laboratory experiment is described that extracts protoporphyrin IX from brown eggshells. The porphyrin is characterized by UV-vis and fluorescence spectroscopy. A chemiluminescence reaction (peroxyoxalate ester fragmentation) is performed that emits light in the UV region. When the porphyrin extract is added as a fluor to this chemiluminescence reaction, an eye-catching deep red glow is emitted from the solution. Using a familiar object, an egg, the experiment touches upon many aspects in chemistry (natural products isolation, structure and photophysical properties of porphyrins, photochemistry). Focus is placed on the understanding of the optical properties of protoporphyrin that enable the final chemiluminescence experiment. This project is appropriate for upper-level organic chemistry students, but might also serve in the advanced physical chemistry laboratory to facilitate a more detailed discussion of photophysical phenomena. Finally, the chemiluminescence experiment is suitable as an impressive stand-alone demonstration.