Chapter 3 pH MEASUREMENT
3.4 Calibration Setting
F-52, 53, 54, 55 53
● NIST mode
After measurement with the standard solutions of pH7 and pH4 (or pH9), the measurement
using the standard solution of pH7 is repeated five times, and the result is displayed. This
check procedure conforms to the regulations by the Japanese Pharmacopoeia (JP).
1. Immerse the electrode into the standard solution, and press CAL key. The mea-
sured values are automatically read.
When the indication value is stabilized, pressing ENTER key also determines the values.
Measure the standard solutions in the following order:
① pH6.865
② pH4.008(or pH9.180)
③ pH6.865
④ pH6.865
⑤ pH6.865
⑥ pH6.865
⑦ pH6.865
●
Wash the electrode with pure water before each measurement.
●
The measured values during periodical check are displayed according to the val-
ues after the calibration is cleared.
When the calibration range error occurs either at step ① and/or ② , the screen displays the
error and the check automatically stops.
2. When the measurement is completed, data is automatically displayed.
●
OK/CHECK judge
Electrode: OK (satisfies regulation requirements)/CHECK (does not satisfy regu-
lation requirements)
●
Calibrated value for each standard solution of pH7, 4, or 9, potential, and temperature.
●
Asymmetric potential (within regulated value ± 30 mV)
●
Sensitivity pH4 to 7(90% to 105% of regulated value)
pH7 to 9(90% to 105% of regulated value)
●
Repeatability(within regulated value ± 0.05pH)
The repeatability shows the difference between maximum and minimum results given by five
measurements using the standard solution of pH7.
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