Appendix – Quality control ABL90 FLEX reference manual
I-10
Temperature corrections (for manual QC only)
Temperature correction is done to ensure that the quality control results reflect
the analyzer performance and are not influenced by fluctuations in the ambient
temperature.
The insert control ranges are determined at a reference temperature of 25 °C.
Deviations from this temperature will have an impact on the following
parameters: pH,
pCO
2
and pO
2
.
The reason for temperature correction is as follows:
An unopened ampoule consists of two phases: a liquid and
a gas phase. Both phases contain molecules of CO
2
and O
2
,
and equilibrium between the two phases is temperature
dependent. As only the liquid phase is measured, it is
important to temperature correct the result to the actual
temperature.
To ensure that the QC result actually reflects the performance of the analyzer and
not just fluctuates because of temperature variations, it is important to keep the
ampoule at a stable and known temperature, so that variations can be corrected
for in the correct way.
The default temperature of a QC measurement is automatically set at 25 C
unless otherwise specified by the user. If the ampoule temperature is not 25 C,
the equilibrium will be different. The lower the temperature, the more O
2
and CO
2
molecules will migrate to the liquid phase, and the
pCO
2
and pO
2
will report too
high values, and the pH a too low value, if the results are not temperature
corrected. If the temperature is higher than 25C, the
pCO
2
and pO
2
values will be
too low and the pH too high, if the results are not temperature corrected. The pH
value will be affected, as an increase of the
pCO
2
will make the quality control
solution more acidic.
Temperature Parameters
pH pCO
2
pO
2
> 25 C
< 25 C
where = higher values, and = lower values.
Radiometer recommends that ampoules that have been stored in a cool place are
conditioned at a known room temperature for at least 5 hours before a
measurement, and we strongly advise not to keep ampoules on the top of an
analyzer as the temperature there can vary.
In the ABL90 FLEX analyzers the software will automatically temperature correct
the results on Radiometer QUALICHECK5+ solutions once the ambient
temperature has been entered.
Radiometer uses a reference temperature of 25 C.
Purpose
Parameters
that require
temperature
correction
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