Camera phone colorimetry provides a facile and quantitative method for determining the concentration of colored compounds. Students use camera phones to collect images of standards and unknowns, quantify the red, green, and blue channel values for each sample in the image by using a simple app, and apply the Beer-Lambert law, also commonly referred to as Beer's law, to quantify the concentration of an absorbing analyte in solution. Absorbance is calculated by taking the negative log of the quotient determined by dividing the channel value for a sample or standard divided by the channel value for the blank. Standard and sample solutions can be arranged in front of screens emitting specific colors in order to test which background color yields the most precise and accurate results. Results from experiments using solutions of blue food dye, lemon-lime sports drink, and iron(III) chloride as well as suspensions of iron oxyhydroxide (figure1) and gold nanoparticles demonstrated that absorbance versus concentration data are linear for data collected using digital cameras and camera phones. The key to success collecting a single image of samples, standards, and blanks arranged in front of the uniform light source, such as a light box or a computer screen. The approach provides an accessible and quantitative method for performing colorimetric analysis in a wide range of settings, from the high school chemistry laboratory, to the field, and to the research laboratory.

Camera phone colorimetry

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.