Mettler Toledo SevenGo pro Mode D'emploi page 23

Under equilibrium conditions, the partial pressure of oxygen in air-saturated water is equal to the
par t ial pressure of oxygen in water-saturated air.
Performing a two-point calibration
The second point of a DO calibration is done with a zero oxygen solution.
1 For the first calibration point follow the steps (a-h) as described above in "Performing a one-
point calibration".
2 Remove the calibration tube.
3 Rinse the sensor with deionized water.
4 Prepare a zero oxygen solution and place the InLab
5 Allow at least five minutes for the sensor to equilibrate prior to calibration.
6 Press CAL.
7 Press End to accept the calibration and return to sample measurement.
8 Press Exit to reject the calibration.
9 Thoroughly rinse the sensor under running water and blot it dry with a lint-free tissue
●
Zero-point calibrations are frequently a source of error. Due to the very low zero current of
METTLER TOLEDO sensors, a zero-point calibration is unnecessary even for measurement at
low oxygen concentrations.
●
If the sensor is sluggish or inaccurate after a zero point calibration, not all of the zero oxygen
solu t ion was removed from the sensor. A very thorough soaking and rinsing of the sensor in
dis t illed water is required to remove all of the zero oxygen solution and restore the sensor per-
for m ance.
51710917_V02.2011_BA_SG9_98_EnFrEs.indb 19
Cal 2 appears on the display.
The meter endpoints according to the preselected endpoint mode, automatically after the
sig n al has stabilized or after pressing READ. The relevant buffer/standard value is shown
on the display.
The calibration result is shown on the display.
Operating the pH/ORP/Ion/DO meter SG98 and DO meter SG9
OptiOx into the bottle.
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