Metrohm 781 pH/Ion Meter User Manual
Page 70
6.2 pH measurement (pH mode)
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Metrohm buffers
T [°C]
pH 4.00 pH 7.00 pH 9.00
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
3.99
3.99
3.99
3.99
3.99
4.00
4.00
4.01
4.02
4.03
4.04
4.06
4.07
4.09
4.11
4.13
4.15
4.18
4.20
4.23
7.11
7.08
7.06
7.04
7.02
7.00
6.99
6.98
6.98
6.97
6.97
6.97
6.97
6.98
6.98
6.99
7.00
7.00
7.01
7.02
9.27
9.18
9.13
9.08
9.04
9.00
8.96
8.93
8.90
8.87
8.84
8.81
8.79
8.76
8.74
8.73
8.71
8.70
8.68
8.67
The other stored buffer tables are described in Section 9.4. During the
calibration the pH/Ion Meter shows the type and temperature-specific
pH value of the recognized buffer. For temperatures within the 5 °C
steps the pH value is linearly interpolated.
buffer type:
special
If you would like to use different buffers from those described,
then you require the exact pH value of each buffer at the tempera-
ture used for calibration. These pH values can be entered here.
During the calibration they can again be adapted before each
measurement.
buffer type:
own
If further temperature-specific pH values are known for such buff-
ers then under
own
you can enter up to five such pH(T) series at
steps of 5 °C. The query starts at 0 °C and finishes at 95 °C or
earlier, if '
OFF
' is entered with <CLEAR>.
If you do not know the pH values for individual temperatures just
enter zero. However, you can also calculate these values by linear
interpolation and enter them. Missing pH definitions will otherwise
be shown during the calibration by negative values; the calibra-
tion will then be interrupted with the error message
buffer
not defined
.