[Histonet] Difference between Neutral Buffered Formalin 10% and NB formaldehyde 3.7 to 4%

[William]

Jenni, we do not "oh dear" you, in fact we congratulate you for coming here to get the answers you need.  Many of us lament the state of affairs in histology today. 

Formaldehyde can not exist as a liquid.   100% Formaldehyde is a gas.  To use it in histology we purchase it as formalin which has a concentration of 37% to a max of 40% formaldehyde. We then make 10% formalin which is 3.7% to 4% formaldehyde. 

Incidentally I have worked with a pathologist who used nothing but 4% zinc formalin very successfully (actually better penetration than 10%NBF) -- invalidating the initial premise of your supervisor. 

Will

Sent from my iPhone

On Oct 5, 2011, at 4:51 PM, Rosie Scrimizzi <rosie_scrimizzi <@t> hotmail.com> wrote:

> concentrated formaldehyde is 37-40% w/v so 10% formalin is 3.7-4% w/v.........same thing......
> 
> yes......oh dear!!
> 
> > From: chapcl <@t> yahoo.com
> > Date: Wed, 5 Oct 2011 16:05:31 -0700
> > To: histotech411 <@t> gmail.com
> > Subject: Re: [Histonet] Difference between Neutral Buffered Formalin 10% and	NB formaldehyde 3.7 to 4%
> > CC: histonet <@t> lists.utsouthwestern.edu
> > 
> > Oh dear. Yes they are the same. 
> > 
> > Sent from my iPhone
> > 
> > On Oct 5, 2011, at 4:03 PM, Jenny Vega <histotech411 <@t> gmail.com> wrote:
> > 
> > > Ok I want to know the diferrence between Neutral Buffered Formalin 10% and
> > > NB formaldehyde 3.7 to 4% . I was taugh at college that they were the same
> > > thing and in the book from Frieda Carson it says that but my supervisor
> > > swears they are different chemicals. In the laboratory she has used 10%
> > > neutral buffered formalin all the time, but when we ran out of it we were
> > > sent NB formaldehyde 3.7 to 4 %she sent it back and we were sent NB
> > > formaldehyde 3.7 to 4% once again. She says that 10% NBF is more
> > > concentrated and pure than 3.7 to 4 % formaldehyde and that the tissues are
> > > going to putrefied if they are put in that solution.
> > > 
> > > Am I wrong or is she wrong? thanks
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