Thermo Scientific Orion ROSS, Руководство пользователя

Страница: 16 / 24

16 | ROSS Ultra, ROSS Ultra Triode and ROSS pH Electrodes
Thermo Scientific Orion
Three Point Temperature Calibration
Electrode
Average
temp. error
0-25°C
Average
temp. error
20-40°C
Average
pH error
0-25°C
Average
pH error
20-40°C
8202BN 0.04 0.03 0.000 0.000
8203BN 0.04 0.01 0.000 0.000
8235BN 0.07 0.06 0.001 0.001
8256BN 0.04 0.06 0.000 0.001
Electrode Interferences
Sodium ions are the principal interference of the pH electrode and
cause increasing error at higher pH (lower hydrogen ion activities) and
at higher temperatures. Because the pH membrane is composed of
special low sodium error glass, error due to sodium is negligible when
measuring at pH values less than 12. When measuring at pH values
greater than 12, add the correction value from the nomograph below to
the observed pH reading.
Typical Sodium Error
Example:
pH reading: 12.10
Sodium concentration: 0.5 M
Temperature: 50°C
Correction: 0.01
Corrected pH reading: 12.11
10
11
12
13
80
70
60
50
40
30
° C 20 0.1 M
25
0.5 M
1 M
2 M
5 M
5 M
0.5 M
0.1 M
1 M
2 M
20 ° C
25
30
40
50
60
70
80
0.70
0.60
0.50
0.40
0.30
0.25
0.20
0.15
0.10
0.08
0.06
0.05
0.04
0.03
0.02
0.01
0.005
pH correction
to be added
Sample
pH reading
sample
sodium
concentration