YSI IQ S ENSOR N ET VARiON Plus 700 IQ - Manual (Page 55)

VARiON
®Plus
700 IQ What to do if ...
8 - 1 ba76000e01 01/2012
8 What to do if ...
8.1 Interpretation of the drift voltage
The drift voltage is influenced by the potential levels of the
measurement electrode and reference electrode. If the potential levels
shift, e.g. caused by aging, both parts can move into the same direction
or into opposite directions. The comparison of the drift voltages of two
or three electrodes enables to draw conclusions concerning the state
of individual electrodes if a matrix adjustment or calibration resulted in
an invalid or considerably deviating drift voltage.
Assessment aids View the calibration history of the combination electrodes. In the
following cases, assessment is relatively easy:
 If the drift voltages of all combination electrodes show the same
trend, i. e. the drift voltages have shifted in the same direction
(positive or negative) by approximately the same amount, this
indicates that the potential level of the reference electrode has
shifted. The reference electrode is possibly highly contaminated or
at the end of its service life.
 If the drift voltages of all combination electrodes do not show a trend
but shift by different amounts into different directions, the potential
level of the reference electrode has not changed considerably. The
invalid drift voltage is probably caused by a defective measuring
electrode. The measuring electrode is possibly highly contaminated
or at the end of its service life.