54
is significant. If this message is displayed, check if you have selected the appropriate calibration
standard.to be tested. Allow time for the electrode to stabilize.
•
Wrong new slope. Please check the standard solution
: this message appears if the current slope
exceeds slope window (50% to 120% of default slope for the corresponding ion charge - see ISE
Theorysection for details). Recalibrate the instrument using fresh standards.
•
Wrong old slope. Press <Clear Cal> to clear old calibration
: this message appears as a result of
an erroneous slope condition. Press
to clear old calibration and restart calibration.
•
Difference between standards temperature is too high. Press <Accept> to update the calibration or
clear old calibration
: this message appears when the difference between two standards temperature is
greater than 5 ºC. Recalibrate the instrument while paying attention to the standards temperature.
63
where:
C
SAMPLE
- the sample concentration;
C
STD
- the standard concentration;
V
SAMPLE
- the sample volume;
V
STD
- the standard volume;
and
V
T
= V
SAMPLE
+ V
STD
∆
E
- the difference of potential from the electrode;
S
- the electrode slope, determined in a
previous calibration;
f
- the stoichiometric ratio between sample
and standard;