A Sensitive Nitrate Ion-Selective Electrode from a Pencil Lead. An Analytical Laboratory Experiment
Tatyana A. Bendikov and Thomas C. Harmon
Department of Civil and Environmental Engineering and Center for Embedded Networked Sensing, University of California, Los Angeles, CA 90095
Nitrate ion is an important environmental and human health analyte and thus its detection and quantification is considered essential. This article summarizes a simple procedure for preparing and testing a nitrate ion-selective electrode based on doped polypyrrole films. Everyday pencil leads were used as a substrate for the electrochemical deposition of polypyrrole. Nitrate-doped polypyrrole electrodes, tested potentiometrically for their response to varying NO3–concentrations, exhibited Nernstian behavior (slopes of 54–55 mV per log cycle of nitrate concentration at T = 22°C), with a linear response to nitrate concentrations spanning three orders of magnitude (0.1–1× 10–4 M of NO3–) and a detection limit of 5 ± 1 × 10–5 M of nitrate. The procedure outlined here has the potential to initiate and motivate students with interests in sensor development, micro-fabrication procedures, advanced monitoring of environmental problems, and creating solutions to those problems.
Supplement
Instructions for student, notes for the instructor, and additional experiments are available.
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first.
Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants.