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Identification of an unknown gold solution

I am the Chemical Hygiene Officer at Norwich University, where I've worked for the past 4 years. We have an old bottle simply labeled "Gold Immersion Solution", and marked as poison on the back. The manufacturer's name is missing. Of course we do not have an MSDS, and none of the current professors seem to know about it. Searching the Internet I'm guessing it is either gold chloride or gold cyanide. Litmus paper initially indicated weak alkali before fading back to neutral. So cyanide is my primary suspect. I'd like to neutralize the solution's hazard, and hopefully precipitate out a few grams of metallic gold, before disposal. I am contemplating using a sodium hydroxide [affil link] or lime solution to raise the pH, then adding calcium or sodium hypochlorite to oxidize the cyanide radical. Hopefully the gold will precipitate sometime during the process. Do you have any suggestions? Thank you.

Robert Stockett
Chemical Hygiene Officer - Northfield, Vermont, USA
September 3, 2010

September 9, 2010

dear sir ,
u first add sodium hydroxide and then zinc dust [adv: item on eBay & Amazon] in this solution .that will precipitate cement silver and gold . wash that residue by hot water and treat with nitric acid to dissolve silver and to get brown coloured gold sponge.

Bhupesh Mulik
jewellery - Mumbai, India

September 23, 2010


If you need to identify gold in an unknown solution, the most appropriate method is to carry out a microchemical test on a drop of solution.
Use Chromatography of the drop , eluent may be n-butanol/HCl 4N , ot Ethyl acetate/Ethanol (1/1) in nitric acid medium (add 1ml)
Gold follows the eluent
Use SnCl2 , p-dimethylaminobenzylidenrhodanine, or other reactive, to identify gold.

With time the gold spot becomes black.

Albert Cau
- Toulon, Var, France

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