Metrohm 781 pH/Ion Meter - Manual (Page 97)

7 Various functions
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variance
If at least 3 calibration buffers have been used then the calibration func-
tion will be calculated as a compensation curve according to the princi-
ple of the smallest mean-square error (linear regression). The resulting
variance will be given here. A more detailed explanation of these calcu-
lations is given in Section 9.2.1.
Each subsequent manual alteration of the calibration data pH(0) and
slope will be documented by the entry ' manual ' against these parame-
ters.
buffer type
The type of buffer defined in the calibration parameters at the time
when calibration was carried out is shown here.
no.of buffers
The number of buffers actually measured is shown here. This can be
lower than that given in the calibration parameters, as a calibration can
be terminated prematurely with <QUIT>; only the buffers which have
already been measured will then be used for the calculation of the cali-
bration data.
cal.table: original, delete n, reset cal
This entry can be used to delete individual buffers from the calibration
table (' delete n ') or to delete all the calibration data of an electrode Id
(' reset cal ').
original
If you use <SELECT> to chose the option '
original ' then all the
buffer data previously deleted with ' delete n ' will be reinserted in
the calibration table and used for calculating the calibration data.
delete n
From a calibration list containing at least 3 buffer entries you can
remove individual buffer data by selecting ' delete n ' and enter-
ing the number of the buffer to be deleted in the following line:
delete n: 1..9
The deleted buffer will then be indicated in the calibration table by
' deleted '. The measuring points of deleted buffers are also indi-
cated in the graphical display by an 'o' instead of a '+'.
You can reinsert all deleted buffers in the calibration table with the
option ' original '.