RADIOMETER FLEX ABL90, Reference Manual

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5. Sensors and optical system ABL90 FLEX reference manual
5-30
Calibration of the pO
2
sensor
The pO
2
sensor is calibrated to determine its sensitivity by measuring one
calibration point during a sensitivity calibration process. Performance of the
sensor from calibration to calibration is checked and during sample or quality
control analysis any drift on sensitivity is checked. The pO
2
sensor is calibrated
on ambient air.
The sensitivity is defined as the percentage of the measured pO
2
on ambient air
compared to the reference value:
2
2
O (meas)
S
O (ref)
p
p

where pO
2
(ref) is the pO
2
tension in ambient air saturated with water vapor:
2 2 2
O (ref) O (p(amb) pH O) p F   
where FO
2
is the pO
2
fraction in ambient air, and pH
2
O is the partial water vapor
pressure of saturated air at 37
o
C, and p(amb) is the barometric pressure.
In connection with the sensitivity calibration performed on ambient air, also the
CAL1 (rinse) solution is measured to obtain a status. This status aims to check
the performed calibration. This is done by comparing the measured value of the
CAL1 (rinse) solution to the reference value of CAL1, given by the smart chip):
2 2 2
O (status,cal) O (CAL1,cal) O (CAL1,ref) p p p  
For every measurement, the pO
2
calibration is checked by comparing the
measured value of CAL1 (rinse) solution to the value obtained on the CAL1
solution of the last calibration (CAL1
CAL
):
2 2 2
O (status,meas) O (CAL1,meas) O (CAL1,cal) p p p  
Introduction
Sensitivity
Status