Leaf chlorophyll extraction

John E. Silvius silviusj at cedarville.edu
Sun Mar 16 16:09:23 EST 2003


David,
With respect to why 50% alcohol might work better for chlorophyll
extraction than 90% alcohol, I would hypothesize that it might have to
do with a more favorable denaturation of plastid and cellular
membranes (e.g. the higher the %H2O, the higher the boiling
temperature).  I base this hypothesis on the fact that I do a demo in
which I begin with boiling water and demonstrate the insolubility of
sunflower leaf chlorophylls in water. (Incidently, by placing the leaf
in the boiling/near boiling water, abaxial side up, you can also show
expansion of the gases within the mesophyll by the appearance of air
bubbles adhering to the lower epidermis.)  Then, I transfer the same
leaf to boiling 70 or 80% ethanol and the extraction occurs within a
few minutes.  I have not compared the success of this extraction with
ethanol alone.

John Silvius
Professor of Biology
Cedarville University

John E. Silvius, Ph.D.
Professor of Biology
251 N. Main St.
Cedarville University
Cedarville, Ohio   45314
E-mail:   silviusj at cedarville.edu 
http://www.cedarville.edu/dept/sm/silvius/index.htm
>>> David Hershey <dh321z at yahoo.com> 03/14/03 10:03 AM >>>
A student observed that geranium leaves to be used for
starch testing decolored better in 50% isopropyl
alcohol than in 90%. The alcohol was heated in a
boiling water bath. All the other variables were the
same. 

Does anyone know why 50% alcohol would be better for
removing chlorophyll than 90% alcohol?


David R. Hershey

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