AW: [Histonet] Hard water.

[Gudrun Lang]

Dear Matthew,
Formaldehyd in aequoes solution undergoes the "Cannizzaro-reaction". Please
google it for further info. In the end the pH is rendered acid with
prolonged storage of unbuffered formalin. Then you have to deal with
slightly acid formalin and that was shown to influence immunohistochemistry.
And unbuffered formalin may lead to even more fragmented DNA than usually
with NBF. 
In tapwater diluted formaldehyde was formerly the usual kind of preparation,
but the acid was neutralized by putting a piece of marble into the
container.
The minerals in tapwater may influence the buffering-action of
phosphatebuffer, but that could be easily shown by ph-measuring of the ready
solution. I don't believe, that additional ions in the fixative from
tapwater have any influence on the fixing action.

Gudrun

-----Ursprüngliche Nachricht-----
Von: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] Im Auftrag von MRI
Gesendet: Mittwoch, 28. März 2012 08:40
An: histonet <@t> lists.utsouthwestern.edu
Betreff: [Histonet] Hard water.

Dear all,

In theory, we should all be using distilled or deionised water for making
our formalin (assuming we don't buy it pre-prepared).  However, I know that
some labs in my area are using tap water.  The water in our area is very
hard ( >4.5 mol/m3 25°d) though it is pH neutral, and I'm curious if anyone
knows what effects this may have on immuno and in-situ.
In our lab, we buffer our formalin according to the method in "Theory and
Practice" by Bancroft and Gamble so I'm assuming others in the area do
too... but I could be wrong, and I'm too frequently an optimist.
Should the buffers counteract negative effects from the minerals in the
water or will they exacerbate the situation and add to the hardness and
reduce the pH level?
Any ideas?

Thanks in advance,

Matthew.

_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet