TCE
    
|
The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 17
(2012) pp 080-082
DOI 10.1007/s00897122421a
Determination of Caffeine in Coffee: An Inexpensive Experiment for High School and College Laboratories
Kirsten Canady and Ray von Wandruszka*
Department of Chemistry, University of Idaho, Moscow,
ID
83844, rvw@uidaho.edu
Received October 31, 2011. Accepted May 3, 2012.
Published: 1 June 2012
Abstract. 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.
Key Words: Laboratories and Demonstrations; general chemistry; coffee; caffeine; paper chromatography; colorimetry; methylene blue
(*) Corresponding author. (E-mail: rvw@uidaho.edu)
Article in PDF format (118 KB) HTML format
© The Chemical Educator 1996-2015