Determination of Caffeine in Coffee

High school and small college science laboratories are often forced to operate with marginal budgets, making it necessary to keep the costs of equipment and supplies very low. In the present work, a low cost experiment was developed in which paper chromatography was used to separate caffeine from coffee and quantify it colorimetrically by reaction with methylene blue. The procedure lends itself to the analysis of different coffees, or methods of preparation, or to a comparison of caffeine content at different stages of the brewing process. Absorbance measurements were obtained with an inexpensive 4-wavelength colorimeter linked to a data logger, but any simple photometer could also be used. The experiment introduces students to fundamental tools and techniques, providing interesting information about a familiar beverage and utilizing inexpensive, nontoxic materials.