Metrohm 781 pH/Ion Meter User Manual
Page 86
6.5 Direct ion measurement (781 only: Conc mode)
76
780/781 pH/Ion Meter, Manual
drift:
0.1...0.5...9.9 mV/min
Just like the ion measurement, the calibration is also drift-controlled.
However, this drift-control cannot be switched off.
report:
OFF, short, full
After the calibration you can automatically output the result in the form
of report. You can choose between the '
short
' version containing all the
relevant data and the '
full
' version, which also shows the measuring
curves as a graph (see Section 7.2.4).
Such a report can also be printed out later together with the calibration
for each stored electrode Id.
calibration interval
OFF, 1...999 h
The pH/Ion Meter can automatically remind you about any recalibration
of the pH electrode which is due. This means that if a calibration is car-
ried out with a preset calibration interval then, when this interval has
elapsed, a message will appear on the display:
cal.interval expired
This message is retained and will be printed out on every measuring
point report until a new calibration has been carried out.
no.of standards 1, 2...19
Up to 19 standards can be used for the calibration of the ion selective
electrode. If only a single standard is used for the calibration then the
program will use the existing value for the slope. This will also be cor-
rected accordingly if the calibration temperature changes. This adop-
tion of the existing slope also applies when a calibration with several
standards is canceled with <MODE> or <QUIT> after the first stand-
ard has been measured and then confirmed with <ENTER>.
However, please note that for the calibration of ion-selective electrodes
at least two standards should be used. The possibility of using a single
standard described above should only represent an absolute excep-
tion.
If three or more standards are used then the variance will be included in
the calibration data. More detailed information about the evaluation is
addition:
manual, auto
For the manual addition of the standard you should enter in the next
calibration parameter lines the concentrations of the standards used
(Conc.1, Conc.2, ...). This data can still be modified during the cali-
bration sequence.
With automatic standard addition the pH/Ion Meter carries out the cal-
culation of the standard concentrations, the preparation of the standard
solutions and their measurement automatically. A requirement is that a
Metrohm Dosimat Plus is connected (connection and Dosimat Plus