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Iron (Fe) in Vitamins

Iron (Fe) in Vitamins
Contributors
cmwoodbridge
Professor of Chemistry | Georgia Gwinnett College
Beyond Benign
Beyond Benign, Inc.
Learning Objets
Summary
This is an improvement over a similar lab published in Harris’ Analytical Chemistry text. Instead of using organics to form reddish solutions, the catechins or polyphenolic compounds in green tea form colored complexes with iron. UV-Vis spectroscopy in conjunction with Beer’s law can then be used to determine the concentration of Fe in vitamin tablets.

Other authors: Davis Winn (Georgia Gwinnett College)
Keyword Tags
Introduction to Green Chemistry
File (PDF, PPT, image, etc)
greener_tea-draft_03jan23.docx
Learning Goals/Student Objectives
In performing this experiment, a student will…
Be able to apply Beer’s law to construct a calibration curve and determine the concentration of a sample.
Be able to assess the accuracy of their analysis by comparison to published data.
Be able to explain why one solvent is a better choice than another (assuming multiple solvents are used).
Object Type
Laboratory experiment
Audience
Introductory Undergraduate
Common pedagogies covered
Hands-on learning
Green Chemistry Principles
Less Hazardous Chemical Syntheses
Safer Solvents and Auxiliaries
Use of Renewable Feedstocks
Safety Precautions, Hazards, and Risk Assessment
If water is used as a solvent, issues with using acids is eliminated.

Fe(SO2)2(NH4)2*6H2O 10045-89-3
Green tea (dry) from supermarket – Lipton Green Tea
Fe supplement from supermarket – Nature Made Iron 65 mg
Teacher Recommendations or Piloting Data (if available)
See attached document

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Submitted by

cmwoodbridge
Published on
Moderation state
Published
Collection
Greener General Chemistry Labs
Time required (if applicable)
I have performed this in a 1 3-hour lab period with students working in groups of 3-4. Most students finished in 2 hours. I would schedule this lab after a short lab or a lab with wait time so students can prep their vitamin sample prior to doing this lab

Comments

Christine Morales
Wed, 03/19/2025 - 19:11 Permalink

This works really well and is so green, I'm going to keep using it for the foreseeable future!  (I'm planning to submit an adaptation of this experiment for a 2nd-year analytical laboratory, which is less inquiry-based but also includes a technology component using Python.)

Creative Commons License
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.