"Frank Fürst" <ffrank at rz.uni-potsdam.de> wrote in message
news:87y9ajq7a4.fsf at pc201-37.biochem.uni-potsdam.de...
> "Emir Khatipov" <khatipovNO at NOuchicago.edu> schrieb:
>> > "D.K." <dk at no.email.thankstospam.net> wrote in message
> > news:akufm4$fui$1 at news.doit.wisc.edu...> > > ffrank at rz.uni-potsdam.de (Frank =?iso-8859-1?q?F=FCrst?=) wrote:
> > > >dk at no.email.thankstospam.net (D.K.) schrieb:
> > > >
> > > >> I might have a glaring hole in my education but this is first time
in
> > > >> my life I hear about difficulties measuring pH ~ 1.5 with a
properly
> > > >> calibrated pH-meter. Is there a problem? What kind? Would you
> > > >> similarly say that pH 12 is unreliable?
> > > >
> > > >At high pH you get an error because the electrode will respond to Na+
or
> > > >Li+ (it's called "Alkali-Fehler" in german, "alkali error" or
something
> > > >like that). But I also have never heard of an error at low pH.
> > >
> > > Yes, this effect is easy to understand. Although I doubt it is
significant
> > > at pH 12 - IIRC, most electrodes' specs claim linear response to 12.
> > >
> > > DK
> >
> > Don't get so emotional, Dima! I was just trying to get the point about
the
> > accuracy knowing how most people in molbio labs would calibrate pH
meters -
> > by one buffer (pH 7) !. I also noticed that most labs buy less expensive
pH
> > meters that cannot be easily calibrated over the whole pH range. For
> > example, if you calibrate the instrument with buffers pH 7 and pH 4 and
then
> > check the reading of the buffer pH 10, you would not get the correct
reading
> > of 10.
>> Ah, that's what it's all about. O.K.
>> We are using buffers of pH 2 and 4, pH 4 an 7, and pH 7 and 10, and
> everybody writes down in which region he or she has calibrated. So I
> guess I'm on the safe side even at pH 1.9 or 1.8
>> Bye, Frank
> --
> [Gesucht war ein MTA für Massenmailing]
> Aus Stabilitätsgründen würde ich es allerdings vorziehen, wenn als
> Server-OS nicht Debian-Linux sondern Windows-95 verwendet wird.
> [Elmar Haneke in debian-user-de@]
Cool. You guys are well organized there.
