Xylem HandyLab 100 - Manual (Page 32)

Operation HandyLab 100
32 ba77062d01 03/2014
4.4.5 pH calibration
Why calibrate? pH electrodes age. This changes the zero point (asymmetry) and slope
of the pH electrode. As a result, an inexact measured value is dis-
played. Calibration determines and stores the current values of the
zero point and slope of the electrode.
Thus, you should calibrate at regular intervals.
When do you have to
calibrate?
 After connecting another combination electrode
 When the calibration interval has expired
Buffer sets for
calibration
You can use the buffer sets quoted in the table for an automatic calibra-
tion. The pH values are valid for the specified temperature values. The
temperature dependence of the pH values is taken into consideration
during calibration.
No. Buffer set * pH values at
1 VariCal
Any Any
2 NIST/DIN
DIN buffers according to DIN
19266 and NIST Traceable
Buffers 1.679
4.006
6.865
9.180
12.454 25 °C
3
TEC
Technical buffers 2.000
4.010
7.000
10.011 25 °C
4
Merck 1* 4.000
7.000
9.000 20 °C
5 Merck 2 * 1.000
6.000
8.000
13.000 20 °C
6 Merck 3 * 4.660
6.880
9.220 20 °C
7
Merck 4 * 2.000
4.000
7.000
10.000 20 °C
8
Merck 5 * 4.010
7.000
10.000 25 °C