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The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 19 (2014) pp 175-181

A Breadboard Filter Photometer/Fluorometer that Illustrates the Effects of Spectral Bandpass on Calibration Curves While Measuring Free-Chlorine in Tap Water and Quinine in Tonic Water

Tyler Tommey, Dustin Wagner, John Shaw Jr., and Michael K. Bellamy*

Department of Natural Sciences, Northwest Missouri State University, Maryville, MO 64468,
Received February 3, 2014. Accepted March 20, 2014.

Published: 6 June 2014

Abstract. Two experiments are presented. The first is a breadboard exercise in which students assemble all or part of a filter photometer that can quantify chlorine in drinking water. Bandpass interference filters can be easily interchanged to demonstrate the effect of bandpass on the slope and the linearity of a calibration curve when measuring the absorbance of electromagnetic radiation. In the second exercise, components of the instrument are rearranged to make a filter fluorometer that quantifies quinine in tonic water. Exchanging filters in the fluorometer varies the intensity of electromagnetic radiation incident on the sample and the intensity of the emitted electromagnetic radiation that reaches the detector. The effects of these changes on the slope of a calibration curve in a fluorescence experiment are then demonstrated.

Key Words: Laboratories and Demonstrations; analytical chemistry; inexpensive spectrometer; bandpass.

(*) Corresponding author. (E-mail:

Article in PDF format (234 KB) HTML format

Supporting Materials:

Two supporting files are available, Notes for Instructors and Laboratory Procedures for Students (1.04 MB).

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