Metrohm 827 pH lab - Manual (Page 41)

6 Methods / Parameters
826/827 pH meter, Instructions for Use
33
6.1.4 pH calibration data
The current pH calibration data can be called up at any time under pa-
ram/cal.data.
If no calibration has yet been carried out then only the theoretical cali-
bration data slope = 100.00 % and pH(0) = 7.000 will be shown and
taken into account for the measurement.
param
:
├
cal.data
: ├
slope
├
pH(0)
├
variance
├
temperature
├
temp.sensor
├
cal.date
├
cal.time
├
cal.interval
├
buff.type
└
no.of buffers
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). Due to the fact that only pH(0) can be calculated af-
ter a single buffer calibration, the slope is set to 100 %.
This value can be altered manually for test purposes.
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.
Note!
The manual alteration of either slope or pH(0) is documented by de-
leting the remaining calibration data.
variance
For the calibration with 3 buffers the calibration function will be calcu-
lated as a compensation curve according to the principle of the smal-
lest mean-square error (linear regression). The resulting variance will be
given here.