And yet another method: Buy Trizma base and Trizma-HCl and keep them
seperate from general lab stock. On page 1052 of the 1997 Sigma catalog,
there is a table that tells you how much to weigh out of each to get a
particular pH at a particular temperature. This way you avoid pH meters,
pH paper etc. Good Luck,
Harry Yim Ph.D.
Dept of Infectious Diseases
Children's Hospital and Medical Center
Seattle WA 98105
hyim at chmc.orghyim at u.washington.edu
fax (206) 527-3890
On 4 Feb 1997, George Rutherford wrote:
> In article <5d6fh0$c1k at light.nih.gov>, bernard at elsie.nci.nih.gov (Bernard
> Murray) wrote:
>> > In article <firstname.lastname@example.org>, jmorlan at SFSU.EDU says...
> > >
> > >Banwari,
> > >
> > >We rinse our electrode in DEPC-treated water. Strictly speaking, this does
> > >not make the electrode RNAse free, but we seldom have any problems doing it
> > >this way.
> > >
> > >-John
> > >SFSU
> > >>Hi!
> > >>While making RNAse free Tris, does the pH electrode have to be
> > >>RNase free for adjusting the pH? If yes, then how do you make an
> > >>electrode RNase free?
> > >>Thanks in advance
> > I'm a little more paranoid and go through the following cycle;
> > a) carefully remove a small aliquot from the main solution
> > b) check the pH
> > c) try and adjust the pH of the main solution
> > until the pH of the solution is correct. You can start out with
> > testing single drops on pH paper until you are within 1 pH unit.
> > I fully admit this may be a little over the top but the pH meter
> > is shared with a lot of people (and I don't trust any of them).
> > ...at least I have yet to start DEPC treating my NaOH and HCl stocks ;-)
> > Bernard
>>> I'm a bit more paranoid still, and wouldn't bother with the meter;I'd
> stick with pH sticks, especially because meters (even using 'Tris
> electrodes') have never seemed all that accurate to me for pH'ing Tris.