From: Alan \"Uncle Al\" Schwartz <email@example.com>
Subject: Re: Q: Iron idicator - Sodium Ferrocyanide?
Date: 24 Jan 1996 18:42:53 GMT
Ferrocyanide will grab just about any divalent transition metal to form
an insoluble and often strongly-colored "Prussian Blue" type of complex.
The levels of free soluble iron, Fe^(2+) in anything are vanishingly
small because of its ready oxidation to insoluble Fe^(+3) hydroxo-oxides
(rust). If there is iron in solution, it is probably complexed and may
be unavailable for your reaction. In any case, nominal levels are only
parts-per-million. There is nothing to be seen.
If you want a nice experiment, take a cup of Total or other "high iron"
cereal, buzz it up in a blender with a few volumes of water to make a
thin mush, then swish a good magnet covered with aluminum foil through
the muck (or pour it into a glass and run a strong magnet along the
side). Son of a gun - iron filings!
Colorimetric determinations generally employ reaction of the desired
species into a derivative which can be solvent extracted from the water
phase and then concentrated, such as nickel dimethylglyoxime or Cuproin
for iron and copper. 18th Century science aside, modern determinations
are usually done by atomic absorption or other physical instrumental
technique which is fast, labor-lite, generates minimal waste, and which
accomodates mostly untreated matrices.
Alan "Uncle Al" Schwartz
UncleAl0@ix.netcom.com ("zero" before "@")
"Quis custodiet ipsos custodes?" The Net!
(Uncle Al has been Officially convinced to "voluntarily" shut down his
homepage in February. You can own his complete 529 essay collection.
Surf by before it dies!)