Frequently asked questions about PH meter
1. What causes the two measurement data of the same sample to be different?
There are two situations that can cause the above problems:
(1) The measured pH value is different due to temperature change, so please keep the measured temperature unchanged.
(2) There is a chemical reaction in the sample itself, which leads to the difference in the measured pH value. Please measure the sample as soon as possible and pay attention to the storage conditions of the sample.
2. What is the reason that it shows 7.00 after calibration with pH6.86 buffer?
The wrong buffer group is selected, and the correct buffer group needs to be reset (see the instrument operation manual). Or during calibration.
The buffer temperature is not at 25℃.
3. Why can't the new electrode be calibrated or the value is unstable?
This may be because there are bubbles in the electrode sensitive film or gel, which leads to abnormal potential change, so it is necessary to remove the bubbles and use force.
Swing the electrode downward (like a thermometer) to drive away bubbles. If it is not used at ordinary times, the electrode can be placed vertically.
Or the electrode sensitive membrane is dried for a long time, and it needs to be activated in 0.1mol/L dilute hydrochloric acid.
4. Why is the electrode measurement unstable?
There may be two situations that can cause the above problems:
(1) Improper electrode selection.
If the response time of the measuring buffer is short, but the measured sample is unstable, it means that the electrode is not suitable for measuring the measured sample (electrode selection
See appendix InLab electrode selection guide).
(2) electrode aging.
The response time of the electrode in the buffer can be tested. If it is longer than 1 minute, the electrode needs to be activated (soaked in 0.1mol/LHCl for one night) or replaced with a new electrode.
