Undergraduate Analytical Chemistry: To Use and Evaluate Organic Chelators for Spectrophotometric Determination of Iron

Abstract

An analytical chemistry laboratory project to use and evaluate pyridyl‐ and triazine‐containing chelators for spectrophotometric determination of iron is described. The “Iron Project” introduces students to UV‐visible spectrophotometry and Beer's law via hands‐on development and use of spectrophotometric methods for iron. Nine chelators are currently available for use. Students perform their proposed work, culminating in formal papers and posters. Student values of molar absorptivities (ϵ_max) and λ_max for ligands 1–9 agree with published values to within ±15% (ϵ_max) and ±3 nm (λ_max) for 75% of results obtained so far. Stoichiometries for Fe(II) chelates of ligands 1–5 are within ±1 mole of ligand of the published ratios. Student work shows a basic understanding of Beer's law as well as a need to improve writing, problem‐solving, and laboratory skills.

Keywords:

• Beer's law
• calibration
• chelate
• iron
• limit of detection
• limit of quantitation
• method of continuous variations
• pyridyl- and triazine-type ligands
• UV‐visible spectrophotometry

Acknowledgments

The author recognizes the immense contributions of the following former CHEM 0260 (Introduction to Analytical Chemistry Laboratory) students to the Iron Project: Fall Term 2001, Amanda Layman, Kimberly Miscik, Carl Santavicca, Edward Smail; Spring Term 2003, Ali Abdullah, Carrie Derco, Amanda Flaus, Gregory Higgins, Ashley Jordan, Michelle Kosakowski, Timothy Ludwick, Thomas Mutzabaugh, Aaron Richter, Holly Sterling, Tera Yingling; Fall Term 2004, Tara Delanoy, Leland Hunter, Brett Marion, Lauren Shustrick; Fall Term 2005, Gina Coffen, Justin Crossey, Autumn Daniels, Jamie Dlugos, Jason Filer, Michael Goodman, Lindsey Littell, David Tkacs, David Todd, Steven Wells. The author gratefully acknowledges the financial support of the McKenna Foundation, the Society for Analytical Chemists of Pittsburgh (SACP), and the Spectroscopy Society of Pittsburgh (SSP) toward the purchase of our UV‐Vis spectrophotometers and the continued support of the Division of Natural Sciences, Mathematics, Engineering, and Computer Science at UPG.

Notes

The author was invited to contribute this paper to a special issue of the journal entitled “Undergraduate Research and Education in Spectroscopy.” This special issue was organized by Associate Editor David J. Butcher, Professor of Chemistry at Western Carolina University, Cullowhee, North Carolina, USA.