Metrohm 781 pH/Ion Meter - Manual (Page 104)

7.1 Calibration and addition/subtraction data
94
780/781 pH/Ion Meter, Manual
variance
With at least 3 additions the compensation curve for U/log(c) will be
calculated according the principle of the smallest mean-square error.
The resulting variance will be given here. A more detailed explanation of
these calculations is given in Section 9.2.2 and Section 9.2.3.
slope
The slope of the calibration function obtained during the addition will be
shown here in mV. With a single addition the slope will be taken from
the current calibration data (see ).
E(0)
E(0) is the potential at log(c) = 0, i.e. the U-axis intercept of the com-
pensation curve in the U/log(c) plot. A more detailed explanation of the
calculations of the calibration data is given in Section 9.2.2 and Sec-
tion 9.2.3.
c ion
Here and in the measured value display the final result of the addition
measurement, the required concentration of the analyte, is given.
The concentration of the ion to be determined in the sample solution is
first calculated from the measured starting potential and the regression
data. Please note that the result itself is calculated taking the calculation
parameters ( smpl.size , V total and factor into account; see also
Section 6.5.4).
date
The date and time of the addition are shown here.
method
The parameters set under
PARAMETER Conc/standard addition
form part of the method parameters. The appropriate method name will
be shown here when the calibration data have been determined using
this method. If no method name has been assigned before the calibra-
tion (see Section 6.1), then ' ******** ' will appear here.
temperature
The temperature of the solution 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 ').