Construction of a Photometer as an Instructional Tool for Electronics and Instrumentation

An introductory electronics laboratory unit for the undergraduate chemical instrumentation course is presented. In this unit, students use basic electronic components to build a functioning photometer. Students interface the photometer to a microcontroller and write an Arduino program to collect the signal, calculate the absorbance, and display the result on a liquid crystal display (LCD). Students use their home-built instruments to measure the concentration of hexavalent chromium in a series of standard solutions and determine the figures of merit: sensitivity, detection limit, and dynamic range of the instrument. They also used their instrument to measure the concentration of hexavalent chromium in an unknown water sample.