The introduction of imaging technologies into chemical and biochemical analysis has revolutionized fields as diverse as atomic spectroscopy and drug discovery. Traditionally, scientific cameras and associated analysis software have been expensive, difficult to use, and not widely distributed in teaching laboratories. Despite the widespread use of imaging technologies in many areas of chemistry, biology, biochemistry, biophysics, and medicine, they are not widely found in the undergraduate laboratory. This article describes a simple, inexpensive, experiment based on quantitative imaging. The experiment allows students to use quenching of fluorescein dianion to measure rate constants near 2 x 109 L mol-1 s. This experiment has been used during four academic years in an intermediate biochemistry course by ∼75 students. In this context, it was used to introduce students to the principles of fluorescence quenching, which is used in a variety of ways in modern biophysical chemistry. It may also be a suitable platform for lab modules for physical chemistry.
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Instructions for the students and notes for the instructor are available.
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