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 ORS - Chemical Safety

Procedure for Deactivation of Ammoniacal Silver Solutions 

Ammoniacal silver staining solutions are hazardous due to the possibility that explosive silver salts may be formed. 

To provide a safe mechanism for disposal and to maintain a safe working environment, the following procedures should be implemented when handling, storing, or disposing of silver solutons. 

  1. Do not allow silver nitrate solutions to remain in an ammonium solution longer than two hours. 
  2. Mix only the amount of silver nitrate solution necessary to complete your procedure. 
  3. Keep prepared solutions of silver nitrate and ammonium hydroxide separate. Mix together only the amounts that you will use immediately. 
  4. If silver - ammonium solutions are generated, the following procedures will deactivate the solutons. 
    1. Dilute the silver/ammonium solution with 15 parts of water for every one part of solution (15:1 water: silver/ammonium solutions).
    2. In another container, make a 5% hydrochloric acid solution. 
    3. Slowly add the HCL solution to the silver/ammonium solution until the pH reaches 2. Stir frequently. 
    4. If there is evidence of heat generation, ice should be added to cool down the process. 
    5. When the pH reaches 2, silver chloride should begin to precipitate out. Filter the recipitate with a Buchner funnel.
    6. Dispose of the precipitate through the Office for Research Safety. 
    7. The pH the liquid waste should be adjusted to 4-5 with the addition of sodium icarbonate. It may then be flushed down the drain with excess water.

 

 

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Last Revision 05/16/2007
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