PH meter frequently asked questions
1. What causes the two measurement data of the same sample to be different?
There are two situations that can cause the above problem:
(1) Temperature changes will cause differences in the measured pH value, please keep the measurement temperature unchanged.
(2) A chemical reaction has occurred in the sample itself, resulting in a 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 why the display is 7.00 after calibration with pH6.86 buffer solution?
The wrong buffer group is selected, and the correct buffer group needs to be reset (see the instrument operation manual). or when calibrating
The buffer temperature is not at 25°C.
3. Why can't the new electrode be calibrated or the value is unstable?
This may be due to the air bubbles in the electrode sensitive film or gel, resulting in abnormal potential changes, so it is necessary to remove the air bubbles, use force
the
Throw the electrode down (like a thermometer) to drive away the air bubbles. If you don't use it normally, you can place the electrode vertically.
Or if the electrode sensitive membrane is left dry for too long, it needs to be activated in 0.1mol/L dilute hydrochloric acid.
4. Why is the measured value of the electrode unstable?
There are two possible situations that can cause the above problem:
(1) The electrode selection is not suitable.
If the response time of the measurement buffer is very 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 (0.1mol/LHCl
Soak overnight) or replace with a new electrode.
