Introducing colorimetric analysis with camera phones and digital cameras: An activity for high school or general chemistry

A common task in chemistry is the determination of concentration of unknown compounds. The Beer-Lambert law, also commonly referred to as Beer's law, enables the quantitation of the concentration of an absorbing analyte in solution. Results from experiments using solutions of blue food dye, lemon-lime sports drink, and iron(III) chloride demonstrated that absorbance versus concentration data are linear for data collected using digital cameras and camera phones. The key to obtaining reliable data is collecting a single image of samples, standards, and blanks arranged in front of a uniform light source, such as a light box or a computer screen. The approach provides a facile method for performing colorimetric analysis in a wide range of settings, from the high school chemistry laboratory, in the field, and the research laboratory.