Hello all,

I am currently updating our staining manual and have come across a confusing issue. We have two methods for colloidal iron (merged hospital scenario).   One method for Colloidal Iron, from Thompson states that pH is critical and adjusting the pH to 1.3 is imperative to prevent non-specific staining. The Muller Mowry method in Carson and Hale's from Culling both make no mention of pH.  I found another reference in Histonet that the ideal pH should be 1.6 to 1.9 for optimal selectivity. This has left me quite confused. Is the pH critical or not?

Obviously, I would like the best method for our lab and preferably with the least amount of work (ie. it would be faster if we didn't need to pH the working solution everytime). 

Can anyone enlighten me on this matter?

Thanks very much,
Susan McFarland
London Health Sciences Centre