The Determination of Ergosterol in Environmental Samples. An Interdisciplinary Project Involving Techniques of Analytical and Organic Chemistry

In this undergraduate laboratory experiment, a naturally formed steroid that is an important environmental indicator of biological activity is extracted and quantified. The target compound is ergosterol, a steroid found only in fungi and an accepted measure of fungal biomass. Maple leaves were used...

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Bibliographic Details
Published in:Journal of chemical education 2000-12, Vol.77 (12), p.1621
Main Authors: Volker, Eugene J, DiLella, Dan, Terneus, Kim, Baldwin, Carson, Volker, Ilona
Format: Article
Language:English
Subjects:
Biological activity
Chemistry
Chromatography
Environmental indicators
Experiments
Fungi
Inhalants
Laboratory Procedures
Leaves
Organic chemistry
Scientific Concepts
Steroids
Student Research
Water
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Summary:In this undergraduate laboratory experiment, a naturally formed steroid that is an important environmental indicator of biological activity is extracted and quantified. The target compound is ergosterol, a steroid found only in fungi and an accepted measure of fungal biomass. Maple leaves were used as a representative sample, but the procedure can be extended to soils, fruits, and grains. The environmental sample is first saponified with methanolic KOH to release ergosterol from any bound forms. Next, the steroid is transferred into pentane to separate it from the polar components of the initial extract. After evaporation of the pentane, the residue containing the steroid is dissolved in methanol and filtered. This solution is analyzed on an HPLC instrument equipped with a reversed-phase column. Typical values for ergosterol in the maple leaf samples analyzed ranged from 22 to 240 μg/g of dry leaf. Leaves collected shortly after falling have low values, and those collected later have progressively higher values. The experiment has been tested in Analytical Chemistry, Environmental Chemistry, and Organic Chemistry classes and can be performed in two 3-hour laboratory periods.
ISSN:0021-9584
1938-1328
DOI:10.1021/ed077p1621