Re: [Histonet] cacodylate vs PBS

From:Geoff McAuliffe

Hi Sharon:

    Rather than believe other's opinions (unless they have references to 
back them up) the only real way to answer the question is to 'do the 
experiment' yourself. The best "ammunition" is real-world results in 
your lab with your antigens. Sodium cacodylate has an advantage as a 
buffer for EM fixation in that you can dissolve calcium ions in it (for 
improved membrane fixation). Calcium phosphate, on the other hand, is 
very insoluble (this fact does not seem to deter some folks from putting 
Ca ions in their phosphate-buffered fix, they happily filter out the 
precipitate and continue on their merry way). Cacolylate has arsenic in 
it and should be disposed of with much greater care than phosphate 
buffers. Cacodylate does seem to last longer before molds begin to grow 
in it.
    After enduring the rigors of paraffin processing,  I would be 
surprised if the choice of buffer made much difference, but it might, 
depending on the antigen in question. 


Sharon Cooperman wrote:

> Hi, histonetters.  There is a debate in my lab regarding which buffer 
> is best for IHC on FFPE tissue.  I use 0.1M PBS made up the usual way 
> (Sorensen's?)  Other people in my lab use NaCacodylate.  I have been 
> told by various people that NaCacodylate is used for some EM purposes 
> and doesn't preserve antigenicity or isn't the best choice for IHC for 
> some other reason.  Does anyone have info or an opinion on this to 
> either set me straight or provide me with ammunition for the next 
> round of arguing?
> Thanks,
> Sharon

Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583; fax: -4029

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