[Histonet] 10% Neutral Buffered Formalin - Methanol?

Mark Ray darkdaym <@t> comcast.net
Wed Nov 17 13:53:32 CST 2010

The Methanol concentration of Formalin, 37% is frequently described on 
the MSDS as 10-15%.  However, I believe the actual Methanol 
concentration is  normally at the low end of that range.  Both 
Formaldehyde  Gas and Methanol are Flammable.

Commercial 10% NBF typically  contains about 1.1% Methanol and 3.7% 
Formaldehyde.  The  Flash Point of this water solution defines it as a 
Combustible Liquid.  It is not correct to call  it or handle as as a 
Flammable Liquid and it does not normally require Flammable Liquid 
storage and precautions.  Let the Safety Officers of your institution 
determine how you should handle and store these quantities of a 
Combustible Liquid.


On 11/17/2010 10:42 AM, Geoff McAuliffe 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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