what ion strength in pH calibration buffer?

Hans-Georg Klieber klieber at mailer.uni-marburg.de
Sat Dec 21 06:58:39 EST 1996


Hi,

my current understanding of pH electrodes is that they
measure hydrogen ion activity in the given solution.

It should therefore not matter if the ion strength of the buffer
solution that was used to calibrate the pH electrode 
is different from the ion strength of the solution where the
actual measurement is taken. The concentration/activity
ratio for hydrogen (and all other ions) would of course be
different in the two solutions - but the pH (=activity) reading
should still be correct.

It has been suggested to me that this belief is not correct.
Could some (expert)  please comment on this?

Thank you,
Hans-Georg Klieber

--
Dr. Hans-Georg Klieber, klieber at mailer.uni-marburg.de
Physiological Institute, University of Marburg, Germany
Office: +49-6421-286521, Home: -25680
http://staff-www.uni-marburg.de/~klieber/






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