Lead is often the culprit in forming precipitates.  Several different lead stains are in use.  Reynolds lead citrate is the one I prefer.  I make it up fresh weekly.  I also place several pellets of sodium hydroxide in the staining dish to absorb atmospheric CO2 which can react with the stain to form insoluble lead carbonate.
Elizabeth

Elizabeth Wurdak, PhD
Biology Department
Saint John's University
Collegeville, MN 56321
Tel: (320) 363-3177


> ----------
> From: 	histonet-bounces@lists.utsouthwestern.edu on behalf of brent hart
> Sent: 	Wednesday, June 21, 2006 4:25 PM
> To: 	histonet@lists.utsouthwestern.edu
> Subject: 	[Histonet] E.M. precipitate
> 
> We are having problems with black precipitate on our E.M. photo's. Does any one mind sharing your procedure with me. It has been checked and it is not bacteria.  We think it is lead?
>    
>   Fax (817) 250-5698
>   Brent Hart
> 
>  		
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