Maybe you could estimate the silver content of the fixer by finding out
how much silver there is in the paper that you're using, multiply by
the amount of paper, and assume/guess that something like half the
silver is in the fixer, the balance remaining in the image.
John
=============
Peter Badcock wrote:
Thanks Howard,
This link
mentions the Volhard method of Argentometry.
And Ralph, I've emailed the maintainers of Australia's PURE
code (PURE=Photographic Uniform Regulations for the Environment) to
seek clarification of their limit. Specifically what mass of silver per
time is permitted to be discharged (I'll be way under that anyway).
rgds
Peter
On 1 February 2010 03:00, Howard Efner <hfefner@xxxxxxxxxxxxx>
wrote:
Peter, see if your library has or can get Scott's _Standard Methods
of Analysis_. It is the Bible of classical analytical techniques. Two
possibilities would be a Volhard titration ( standardized ammonium
thiocyanate and a iron indicator - silver thiocyanate precipitates
until the end point then the red iron thiocyanate complex is formed to
indicate the end point.) I do not know if it is sensitive enough for
50 ppm. Ion chromatography is a possibility but the equipment is not
cheap.
Looks like this is another application of the impossible triad:
GOOD
FAST
CHEAP
Pick any two.
Howard
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