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convenient, because it is possible to switch between
different nitrous oxide levels without changing the water.
Calculate the appropriate mixture from the solubilities
given in Table 2. Alternatively, use the N2O calculator in
the Unisense software (Tools - N2O Calculator) or the Unit
Converter on the Unisense website: Click “Knowledge” -
“Unit Converter”.
For obtaining correct concentrations it is important that
the headspace above the water in the calibration chamber
is closed except for one hole, which should be only slightly
larger than the microsensor shaft. This effectively prevents
ambient air from entering the vessel. We recommend the
Unisense Calibration chamber, CAL300, and rubber stoppers
for calibrations.
b) Add a defined volume of nitrous oxide saturated water to a
defined volume of water in a calibration chamber. For instance
adding 3,679 ml of nitrous oxide saturated to 996,32 ml water gives
a concentration of 100 µM at 22°C (calculated from Table 2), as
3,679 ml of nitrous oxide saturated water contains 100 µmol nitrous
oxide. Using a calibration chamber containing 200 ml, reduce the
volume of added nitrous oxide saturated water by a factor of 5 for
obtaining 100 µM, and so on. After adding nitrous oxide-saturated
water to the calibration chamber, mix it thoroughly for a few
seconds and read the signal when it is stable.
C
alibr
ation chamber
C
AL
300
