formaldehyde pH

David Glover D.J.Glover at
Wed Mar 29 09:47:43 EST 1995

In article <9503232122.AA20689 at infdisease> hyim at SOL.CHMC.ORG (Harry Yim) writes:
>From: hyim at SOL.CHMC.ORG (Harry Yim)
>Subject: formaldehyde pH
>Date: 23 Mar 1995 13:28:12 -0800


>I understand the for RNA formaldehyde gels, the pH of the formaldehyde should be
>above 4 or it is no good.  All the bottles in the department turned out to have
>a pH between 3.3 and 3.6 so I ordered a new bottle of 37% formaldehyde.  Today
>it arrived and it turns out to have a pH of 2.33!  The technical service rep was
>of no use so I hope someone out there can help me.  Should I not worry about the
>pH or can I de-ionize it to get rid of the formic acid (I presume that this is
>what is loering the pH)?  Than
>ks for any help.

>Harry Yim


          I too went through this process some time ago. I searched high and 
low for a bottle of formaldehyde with a pH > 4 but without success.The only 
reason it concerned me at the time was because I was having problems with my 
formaldehyde gels. However, my RNA gels work fine now with formaldehyde pH < 4 
(about 3.5 last time I checked) so I don't worry about it.

David Glover
School of Biochemistry
University of Birmingham, UK

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