Optical Sensors for Manual and Automatic Titration in Undergraduate Laboratory

ABSTRACT

The classic undergraduate titration analysis is upgraded using instrumental detection of end point with color indicators. Several color sensors (CCD-based spectrophotometer, video camera with RGB digitalization, photodiode with appropriate filters) were tested in order to replace the visual indication of the end point with different indicators. The developed procedures show adequate characteristics such as a short titration time and accuracy of 0.1–1%. Specific features of particular titrations such as hardness of water and argentometric titration of chloride are discussed. In the author's opinion, this experimental setup represents an affordable ($100-level) option for an undergraduate or advanced high school chemistry laboratory.

KEYWORDS:

• CCD spectrophotometer
• indicator
• optical sensor
• photodiode
• titration

ACKNOWLEDGMENTS

This laboratory setup was tested with chemistry and forensic chemistry students at SUNY College at Buffalo in 2006–2008. Without their patience and helpful comments, this project could not be accomplished. The financial support from OceanOptics Inc, Vernier Software & Technology, and SUNY SCAP 2007 grants is gratefully acknowledged. The author thanks Dr. Monde Qhobosheane (OceanOptics Inc.) and Jack Randall (Vernier Software & Technology) for helpful advice.