Hi everyone,
I need to order paraformaldehyde (PFA) to prepare a 4% solution to fix cells for immunocytochemistry (IC)
In Signa webpage there are so many product and the prices vary so much. I don't know what to choose. A powder with >95% purity is good enough for IC, isn't it?
Thanks

Below I pasted characteristics of the product I am thinking to buy.


Properties:

vapor density 1.03 (vs air)

vapor pressure <1.45 mm Hg ( 25 °C)

grade purum

assay ≥95.0% (T)

autoignition temp. 572 °F

expl. lim. 73 %

mp 120-170 °C(lit.)

120-170 °C

density 0.88 g/mL at 25 °C(lit.)

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By the way what is the difference between paraformaldehyde and formaldehyde?.
Sorry for ignorance but my chemistry lessons are unfortunatly long forgotten.
Thanks

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This is what we use in the lab. this not from sigma.

AA36606-30, Paraformaldehyde powder 250g (Alfa Aesar), 12.1

Someone posted a website in this forum abt the PFA and FA so I am just copying and pasting.

http://publish.uwo.ca/~jkiernan/formglut.htm

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Hi Scolix,
thank you very much, very interesting.

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Hi there,
I think most people do cell fixation by using 3.7% Paraformadeyde
but some people use 2% only.
can anybody tell me if you tested both and know what is best?
Thanks

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We used to use 3.7% formaldehyde for fixing cells. The formaldehyde solution comes as 37% so we dilute it 10 times to 3.7%, its easier.

I donot know for what people use 2% PFA.

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we use 4% on tissue (ours comes as powder so it maybe someone a long time ago couldnt be bothered with the 0.3%)

dom

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for tissue, I prefere to use 4% PFA freshly dissolved and filtered..to avoid small precipitates than are brighter and bad! for cells also I use 4% PFA but from liquid..it works nicely and so you do not have to bother to prepare it every time....

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not sure i'd trust a ready made liquid due to its photosensitivity - it always gets freshly made as when i didnt the experiments didnt work as well

dom

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We buy 16% PFA and dilute it to 4% for fixing cells. Once diluted to 4% we donot store it for more than 4 weeks. If its still 16% PFA, we can store for a few months.

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