[Histonet] refrigerating sliver and gold chloride??

John Kiernan jkiernan <@t> uwo.ca
Fri Aug 21 16:00:28 CDT 2009

There was never any reason to refrigerate "gold chloride" or silver nitrate. These compounds (solid or dissolved) can be kept for many years at room temperature. 
If the solutions are used repeatedly they eventually deteriorate from contamination with bits of sections, causing a changed appearance. Gold solutions take on a greenish grey hue and flakes of metallic gold eventually settle out. These can easily be recovered and recycled to make "gold chloride" (HAuCl4) again. Clean "gold chloride" solutions keep for ever. I have a few bottles of 0.5% that are still that beautiful yellow colour after about 25 years.
Old silver nitrate looks a bit grey, not completely colourless. Re-purifying in a histology lab isn't really feasible. You can precipitate out and collect the silver, but (strangely) refining companies don't want it. Your message mentioned "silver and gold chloride". I don't know a histological use for silver chloride, which is very sensitive to light - goes grey-violet as you look at it. 
John Kiernan
Anatomy, UWO
London, Canada
= = =
----- Original Message -----
From: Cheri Miller <cmiller <@t> physlab.com>
Date: Friday, August 21, 2009 12:10
Subject: [Histonet] refrigerating sliver and gold chloride??
To: "histonet <@t> lists.utsouthwestern.edu" <histonet <@t> lists.utsouthwestern.edu>
Cc: "histonet-bounces <@t> lists.utsouthwestern.edu" <histonet-bounces <@t> lists.utsouthwestern.edu>

> I just noticed that my silver and gold chloride says to store at 
> room temp now. I have always stored them in the refrigerator. Is 
> anyone still doing this?? Old habits die hard. I want to know if 
> this has caused any staining issues for anyone.
> Cheryl Miller HT (ASCP)
> Histology Supervisor
> Physicians Laboratory,P.C.
> Omaha, Ne.
> 402 738 5052
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