Metrohm 781 pH/Ion Meter - Manual (Page 96)

7.1 Calibration and addition/subtraction data
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780/781 pH/Ion Meter, Manual
method
The calibration parameters set under
PARAMETER pH/calibration
parameters form part of the method parameters. The corresponding
method name will be shown here if the calibration data has been ob-
tained with this method and the resulting quantities slope and pH(0)
have not been altered since. If no method name has been issued be-
fore the calibration (see Section 6.1) then ' ******** ' will appear here.
slope
The slope of the linear calibration curve obtained during the calibration
will be shown here as a percentage. This is a relative quantity which is
based on the temperature-specific value of the Nernst constant (e.g.
59.16 mV at 25 °C). Without a calibration, or after a single buffer calibra-
tion, this is set to 100 %.
This value can be altered manually for test purposes. However, after-
wards the information about the method will be missing from the list
and from the calibration data report. The calibration date and time will
be updated and the temperature information and the calibration table
(see below) will be removed. In addition this action will be documented
by the entry ' manual ' under CAL.DATA/variance .
pH(0)
This is the second characteristic quantity of the calibration curve. pH(0)
is the pH value at 0 mV. It can also be altered manually for test purpos-
es. The other entries under CAL.DATA will be altered in the same way as
for a manual alteration of the slope (see above).
temperature
The calibration temperature is shown here.
temp.sensor
If the calibration temperature has been determined automatically by a
connected temperature sensor then its type will be shown here
(' Pt1000 ' or ' NTC '). A manually entered temperature for the calibration
will be indicated accordingly (' manual ').
c.dat.
The date and time of the calibration is shown here.
cal.interval
If a calibration interval has been defined under
PARAMETERS pH/ cal-
ibration parameters/cal.interval then it will be shown here. It
can be used together with the calibration time given under c.dat . to
estimate the time that the next calibration is due.