Re: paraformalin again

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John Carroll Dennis wrote:
A 4% paraform./PBS prep has gotten out of hand.  The paraformalin will not
go into solution.  The pH is at least 10 (by ph paper).  Temp. is 65
deg. C.

I decided to use NaOH pellets this time.  I don't know why.  Normally, I
use 10 N NaOH.  Never have I seen this problem.

Any ideas?

Does anyone know at what pH paraformalin goes into solution at between 60
and 70 deg. C?
Dear John,
To avoid problems with depolymerization I always prepare 2x conc.
paraformaldehyde in distilled water. Bring to 65 degrees C and add a few
drops of 10M NaOH to clear. After that I dilute 1:1 with a 2x concentrated
buffer of choice, e.g. PBS.

Peter van de Plas
Costerweg 5
6702 AA Wageningen
The Netherlands
phone: (31)-317-497676
fax: (31)-317-415955

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