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.
Regards,
Mark
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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