Au+++ !!! I was using an ICP standard which was probably in the form
of Au+. Thanks for clearing that up for me, Otto.
Duane Miller
Analytical Lab Manager
APL Engineered Materials, Inc.
Urbana, IL
"PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's)."
<[log in to unmask]> wrote on 01/26/2010 04:40:59 PM:
> The gold was supposed to be added as Au+++, which is also an oxidizer
> and hence contributes to keeping Hg in solution.
>
>
> Dr. Otto Herrmann, Ph.D., C.Chem.
> Manager, Analytical and Environmental Services,
> Kinectrics Inc.
> 2-800 Kipling Ave., (Unit 2), Bld. KJ135
> Toronto, ON
> Canada
> M8Z 6C4
> Phone: 416-207-6262
> Fax: 416-207-5550
> e-mail: [log in to unmask]
>
> -----Original Message-----
> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).
> [mailto:[log in to unmask]] On Behalf Of Pappas, Richard
> Steve (CDC/CCEHIP/NCEH)
> Sent: Tuesday, January 26, 2010 5:24 PM
> To: [log in to unmask]
> Subject: Re: gold and silver
>
> It sounds like a Christmas song that Burl Ives (who?) used to sing,
> "Silver and gold, silver and gold..."
>
> The principal behind adding gold is that it is also a soft acid cation
> like mercury. Anything mercury might stick or coordinate with, gold
> would too. By having the gold in excess, one blocks "sticky sites." In
> addition, both Hg and Au are easily reduced, so by having gold in
> excess, the Au is more likely to be reduced by any reducing substance
> than the Hg. Silver is also a soft acid cation and easily reduced, so
> the principal would be the same with certain caveats(!!).
> Silver is easily reduced even by exposure to light. I don't know the
> procedures that you found, but be aware that as a long term solution
> stabilizer, gold would probably be your better choice. Light exposure
> catalyzes reduction and precipitation of silver. As the metallic silver
> comes out of solution, Hg may amalgamate with it or otherwise stick to
> the precipitate.
> I agree with Duane. Chloride in high concentrations, especially > 1.2 M
> (though lower concentrations still help). This takes Hg2+ toward the
> [HgCl4]2- complex. By shifting the equilibrium away from free Hg2+ ion,
> one shifts the equilibrium away from metallic mercury. Ag, however is
> not soluble at some Cl- concentrations. There ARE higher chloro
> complexes with Cl- that are soluble, but hitting that without losing any
> and keeping it there through dilutions may not be easy. I would stick
> with Au, or choose a soluble chelator with a sulfur ligand like
> pyrrolidinecarbodithionic acid ammonium salt (APDC) if you want
> something other than HCl. APDC requires much less.
>
> R. Steven Pappas, Ph.D.
> Emergency Response & Air Toxicants Branch
> Centers for Disease Control & Prevention
> 4770 Buford Hwy. NE, M.S. F-44
> Atlanta, GA 30341-3717
> Phone 770-488-4661
> [log in to unmask]
>
>
> -----Original Message-----
> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).
> [mailto:[log in to unmask]] On Behalf Of Michael Murphy
> Sent: Tuesday, January 26, 2010 4:57 PM
> To: [log in to unmask]
> Subject: gold and silver
>
> Dear All,
>
> I have a question regarding stabilizing Hg solutions with silver. I
> have
> had good luck with stabilizing Hg solutions with Au (both as chloride
> and
> nitrate salts) and in fairly concentrated hydrochloric acid solutions.
>
> However, I have come across a method indicating the use of silver
> instead
> of gold. I am not familiar with this and have not been able to find a
> ready reference. Does anyone have experience with this arrangement?
>
> Always willing to learn something new ....
>
> Thanks,
>
> Michael Murphy
> Research Scientist
> Intertek USA
> Whitehouse, NJ
>
>
>
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