A Green Approach to Separate Spinach Pigments by Column Chromatography

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Chromatography has been a fundamental technique used for chemical separation that dates back to the 1850s. Specifically, column chromatography, typically taught in introductory organic chemistry laboratories, traditionally involves the use of halogenated or harmful solvents, which novice students often overuse. This situation runs contrary to the principles of responsible chemical and waste management emphasized by the green chemistry movement. Since this movement began, conventional means of separation using harmful solvents have been modified to emphasize the need for safer, less hazardous materials and the generation of such waste. The current experiment emphasizes the green chemical principles of renewable feedstocks and recycling to minimize waste, while simultaneously introducing or reinforcing common organic techniques, including solvent extraction, column chromatography, and thin-layer chromatography for the isolation and identification of photosynthetic pigments from spinach leaves. Students gain practical experience processing plant material to isolate and identify the pigments, β-carotene, xanthophylls, and chlorophyll a, using the solvents hexane and acetone. This experiment was designed for use as a standalone single-session lab or, alternatively, it can be coupled with an experiment to recycle waste acetone to further emphasize sustainable practices.