A Colorful Quantification of Antioxidants in Tea: A First-year Undergraduate Laboratory Experiment

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 21 (2016) pp 273-277

A Colorful Quantification of Antioxidants in Tea: A First-year Undergraduate Laboratory Experiment

Manori Perera*

Department of Chemistry, 201 E. Beecher Street, Illinois Wesleyan University, Bloomington, IL 61701, mperera@iwu.edu
Received June 22, 2016. Accepted September 27, 2016.

Published: 16 November 2016

Abstract. 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.

Key Words: Laboratories and Demonstrations; general chemistry; research-based; guided inquiry method; Beer’s law; novel undergraduate lab; tea; antioxidant

(*) Corresponding author. (E-mail: mperera@iwu.edu )

Article in PDF format (187 KB) HTML format

Supporting Materials:

The pre-lab writing exercises, experimental procedure, pre-lab lecture, a supporting document with guidance on developing a scientific manuscript, and the grading rubric are included. A sample lab report of a student is also available. (4.93 MB)