A Colorful Quantification of Antioxidants in Tea

The number of General Chemistry experiments where students ask and answer research questions is rather small. A new research-focused experiment, the quantification of antioxidants present in tea, is described here. Colorimetric methods were used to quantify flavonols and theaflavins, the two types of polyphenol present in tea. Students measured the concentration of these antioxidants in green, black, and 20-year-old black bag tea, two varieties of bottled tea, and one tea variety of their choice. In doing so, students become familiar with applying Beer’s law to determine an unknown concentration of a chemical. Due to its health related theme, this experiment captures the interest of pre-medical students in General Chemistry. At the same time it challenges students in new ways due to a departure from traditional lab procedurals and the introduction of comprehensive writing component. Students learn to develop a detailed lab protocol based on chemical literature and effectively communicate their findings in a journal article format. We report on the design of the lab, the experimental procedure, steps in the data analysis, and a discussion based on student’s progress with regard to three learning goals.