1. The amount of pH correction at the third point mainly depends on your sample situation. As mentioned earlier, there are many calibration solutions available from pH 1.68 to 12.46, and the appropriate calibration solution is chosen based on the final pH range of the sample. We commonly use 4.00, 6.86, and 9.18. If your sample is more alkaline, you need 9.18, 10.01, and 12.46. The calibration sequence varies depending on the situation of different instruments. Some require calibration in sequence, while others do not. The instrument will automatically recognize it and please refer to the relevant instrument user manual.

2. No matter what type of pH meter it is, the point of pH=7 must be corrected, and the point of pH=7 must be corrected first when calibrating at two points. Starting from 7.0, the selected standard solution is related to the pH value of the solution to be measured, so that the pH value of the solution can fall within the calibrated pH range. Generally, two points are sufficient to meet the requirements, and the third point is only considered if the requirements are high. Some instruments can calibrate three points and have a mode to choose from, which can be used directly. For some that are not available, it is generally done through two point and two point proofreading, which means proofreading twice.

3. We usually use a calibration sequence of 7,4,10. First calibrate the acidity and then calibrate the alkalinity.

1. When the electrode is not in use, fully immerse it in the electrode protection solution. The electrode protection solution should be replaced in a timely manner, once a week. Do not soak or soak in pure water with detergent or other absorbent reagents.

2. When measuring solutions with high concentrations, try to shorten the measurement time as much as possible, and carefully clean them after use to prevent the measured solution from adhering to the electrode and contaminating it.

3. After cleaning the electrodes, do not use dust-free paper to wipe the glass film. Instead, use dust-free paper to dry it to avoid damaging the glass film, preventing cross contamination, and affecting measurement accuracy.

4. During measurement, pay attention to that the silver Silver chloride internal reference electrode of the electrode should be immersed in the chloride buffer solution in the bulb. When the external reference solution is less than 1/3, it should be added in time to avoid the number jumping phenomenon in the electrode display part. When using, be careful to gently shake the electrode a few times.

5. Electrodes should not be used in strong acids, alkalis, or other corrosive solutions.

6. It is strictly prohibited to use it in dehydrating media such as anhydrous ethanol, Potassium dichromate, etc.

7. The pH standard buffer should be sealed and stored in a dry place.

8. The transferred standard buffer solution must be stored in a clean and dry container. During each calibration, the electrode should be washed clean and sucked dry with dust-free paper to prevent contamination and dilution of the standard buffer solution. After using the standard buffer solution, it should be sealed with a sealing film and placed in a dry place for multiple uses. When turbidity, mold, or precipitation are found in the transferred standard buffer solution, it cannot be used again.