[Histonet] 10% Neutral Buffered Formalin - Methanol?

[Geoff McAuliffe]

Serra's fixative does have water in it, the water is from the 
formaldehyde. 37% formaldehyde is water saturated with formaldehyde gas 
to about 37%.
The precipitate is probably from the buffering compound, phosphate perhaps.

Geoff

Emily Sours wrote:
> A related question:
> I was making Serra's fix (which has no water in it) and I tried to use
> buffered formalin.  This turned the solution white (which happens when
> Serra's has water in it).  Another brand of formalin (which did not
> say it was buffered) worked fine.
> What's in the buffering that has water in it? Is the methanol diluted
> with water in buffered formalin?
> The recipe for Serra's is
> 6ml 100% EtOH
> 3ml 37% formaldehyde (aka formalin)
> 1ml glacial acetic acid
>
> Perhaps the buffer in your buffered formalin is causing the
> problem--maybe you need unbuffered formalin.
>
> Emily
> --
> Outside of a dog, a book is man's best friend. Inside of a dog it's
> too dark to read.
> --Groucho Marx
>
>
>
> On Wed, Nov 17, 2010 at 11:42 AM, Geoff McAuliffe <mcauliff <@t> umdnj.edu> wrote:
>   
>> Commercially purchased 37% formaldehyde has had a small amount (about 1.5% I
>> think) of methanol added to it for many, many years. It helps to prevent the
>> polymerization of formaldehyde into insoluble paraformaldehyde. It certainly
>> does not make the stock solution flammable and it is not contributing to
>> drying out of your tissues. Those who want methanol-free formalin make it
>> from paraformaldehyde but for LM there is no point.
>>
>> Geoff
>>
>>
>> Jones, Laura wrote:
>>     
>>> Greetings to all of you in Histoland.  Our lab recently switched from
>>> using a formalin substitute to using 10% Neutral Buffered Formalin.  Our
>>> Pathologists have been unhappy with the small tissues, like GI biopsies and
>>> prostate cores.  They say they are seeing too much chatter and poor nuclear
>>> detail.  We have adjusted our processing times with only mildly better
>>> results.
>>>
>>> Today, I arrived at work to find staff cramming boxes and boxes of
>>> prefilled formalin vials into flame cabinets, as JCAHO is here this week.
>>>  It occurred to me that 10% NBF was not considered flammable when we used it
>>> years ago, and I was surprised to find that the MSDS for the bottles we had
>>> ordered listed methanol as an ingredient.  I immediately went back to my
>>> early days in Histo, when we made up 10% NBF ourselves from 37% concentrate;
>>> and we did not have any alcohol in our "recipe".  I thought I had discovered
>>> our whole problem!  However, upon further research, we have found that most
>>> prefilled bottles DO contain methanol.  The large 20 litre cube, however
>>> does not list methanol as an ingredient.
>>>
>>> So, my questions are many.  Does that inclusion of methanol contribute to
>>> the drying out of tissues that we are seeing?  Does anyone sell prefilled
>>> bottles that contain methanol-free formalin?  And, finally, does anyone have
>>> any other thoughts or suggestions?  I should add that we use Toluene as our
>>> clearing agent, because our former Pathologist believed it was less harsh on
>>> the tissues; and we are running our tissues on the Thermo Excelsior.  We are
>>> running small biopsies and large pieces of tissue together, which I know is
>>> not optimal, but we are a small hospital and one processor is it!  I am not
>>> a chemist and would appreciate any advice.  Thanks in advance.
>>>
>>>
>>>
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>> --
>> --
>> **********************************************
>> Geoff McAuliffe, Ph.D.
>> Neuroscience and Cell Biology
>> Robert Wood Johnson Medical School
>> 675 Hoes Lane, Piscataway, NJ 08854
>> voice: (732)-235-4583 mcauliff <@t> umdnj.edu
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-- 
--
**********************************************
Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583 
mcauliff <@t> umdnj.edu
**********************************************