Accurate measurement and reporting of pH data
has been a long-standing problem due to the
effects of temperature. An increase in any
solutions’ temperature will cause a decrease in
its viscosity and an increase in the mobility of its
ions in solution. An increase in temperature may
also lead to an increase in the number of ions in
solution due to the dissociation of molecules
(this is particularly true for weak acids and
bases). As pH is a measure of the hydrogen ion
concentration, a change in the temperature of a
solution will be reflected by a subsequent change
in pH(1).
In addition, changes in temperature will also
have an influence on the measuring senosr used.
Overall, the effects of temperature can be
divided into two main categories:
• Temperature effects that diminish the
accuracy and speed of response of the
Electrode.
• Temperature Coefficient of Variation effects
on the material being measured by the
sensor, whether it be calibration buffer or
sample.
Further sub-classification is necessary for each
of these categories in order to understand the
cause of the problem and determine the optimal
remedial action.