A Brief Discussion on the Maintenance and Precautions of pH Meters

This test pen has been calibrated before leaving the factory and can be used directly. The following situations require recalibration:

Used for a long time after calibration;

Electrode usage is particularly frequent;

The measurement accuracy requirement is relatively high;

Do not reuse calibration buffer when performing calibration;

When there are white crystals on the tip of the pen, it is a normal phenomenon. Please do not be nervous and soak it in water for a period of time;

Drop a few drops of preservation solution or calibration buffer into the pen holder. Do not soak or store the test pen in distilled water or pure water;

There may be small bubbles in the sensitive bulb of the test pen glass electrode, which will affect the normal measurement of the electrode. When using, shake the electrode to make the bubbles run out of the sensitive bulb;

Glass electrodes are prone to breakage, so be careful when using them;

If the displayed value is blurry or not displayed, or if the displayed value is much higher or lower than the true pH value of the solution, the battery should be replaced.

2. Methods for replacing batteries:

Gently pull out the black board with a switch on the pen, without breaking the wires. You can see four 1.5V batteries. Simply pull out and replace them;

Pay attention to battery polarity and choose batteries of the same model;

When inserting the electrode into the test solution or calibration buffer, it should not exceed the height indicated on the test pen.

If the electrode is left for a long time and the sensitive bulb is exposed to air, the response will slow down and the displayed value will be unstable due to the electrode drying At this point, the electrode should be immersed in distilled water to activate for a few hours;

To improve performance, at least once a weekPH meterInsert the electrode into distilled water for a few minutes each time;

The protein precipitate should be immersed in a solution of gastric protease and hydrochloric acid for elimination treatment; This solution should be prepared before use. After use, immerse the electrode in this solution for a few hours, then rinse with clean water, and finally immerse it in distilled water for a few hours;

The oil film also affects the measurement of sensitive bubbles. Li removed this film, washed the sensitive bubbles with a 75% alcohol solution, wiped them dry with filter paper, rinsed them with water, and then immersed them in distilled water for several hours.

3. PH calibration

Immerse the test pen electrode into a mixed phosphate standard buffer solution with a pH value of 6.86 and gently shake it;

Adjust the calibration potentiometer with a small screwdriver until the displayed value matches the pH value of the standard buffer solution at ambient temperature;

Insert the electrode into a standard buffer solution of potassium hydrogen phthalate at pH 4.01 or borax at pH 9.18;

The displayed value should be within the allowable range of error compared to the pH value of the buffer solution.

4. Operation steps and methods

Remove the protective cover;

First, clean the electrode of the pH meter with distilled water and use filter paper to absorb the moisture attached to the electrode;

Connect the switch located on the battery compartment;

Translate into EnglishPH meterInsert the electrode into the measured liquid until the liquid is slightly below the "immersion line". If conditions permit, the solution can be immersed to a position slightly above the "immersion line";

Gently stir the solution until the value stabilizes, then read the displayed value;

After use, clean the electrode, turn off the switch, and put on the protective cover.