NAVI D-25 Instruction Manual page 196

● Precautions when measuring actual samples
D-52/53/54/55
7.2 mV (oxidation-reduction potential [ORP]) measurement
If the prepared ORP standard solution is allowed to
stand in open air for one hour or more, it may undergo
transformation. For this reason prepared ORP standard
solution cannot be stored.
When measuring a solution that has low concentrations
of oxidants and reductants after conducting an
operational check using a standard substance, the
measured values may not stabilize or the results of
measurement might not be repeatable. If this is the case,
use the meter after immersing the electrodes in the
solution again and mixing it thoroughly.
・ Note that when measuring the ORP of a solution that
has extremely low concentrations of oxidants and
reductants (such as tap water, well water, or water
treated with purifying equipment), there may be less
responsiveness,
general.
・ When alkaline water is allowed to stand, its ORP
undergoes considerable changes. Always measure
alkaline ION water promptly.
repeatability, and
7 Reference
stability, in
185