Preparation and storage of standard buffer solution
1. pH standard materials should be stored in a dry place. For example, mixed phosphate pH standard materials will deliquesce when the air humidity is high. Once deliquescence occurs, the pH standard materials cannot be used.
⒉ When preparing the pH standard solution, double distilled water or deionized water should be used. If it is used for 0.1 level pH meter measurement, ordinary distilled water can be used.
⒊When preparing the pH standard solution, use a smaller beaker to dilute it to reduce the pH standard solution sticking to the wall of the beaker. Plastic bags or other containers storing pH standard substances should not only be poured clean, but also rinsed with distilled water several times, and then poured into the prepared pH standard solution to ensure that the prepared pH standard solution is accurate.
⒋The prepared standard buffer solution can generally be stored for 2-3 months. If it is found to be turbid, moldy or precipitated, it cannot be used further.
⒌The alkaline standard solution should be stored in a sealed polyethylene bottle. Prevent carbon dioxide from entering the standard solution to form carbonic acid and lower its pH value.
Features of pH standard buffer solution:
The pH of a standard solution is known to a specified accuracy. The pH value of the standard solution has good reproducibility and stability, has a large buffer capacity, a small dilution value and a small temperature coefficient. The solution is easy to prepare.
1. PH 4.003, 25 degree potassium hydrogen phthalate can prepare 250ML solution
2. PH 6.864, 25 degree mixed phosphate can prepare 250ML solution
3. PH 9.182, 25 degree boric acid can prepare 250ML solution
4. Electrode soaking solution: 3M potassium chloride solution
The storage time of the standard buffer solution of the pH meter is about 2 to 3 months. Check whether the standard buffer solution of the pH meter has expired. You should observe whether there is turbidity, mold or precipitation in the solution. Once the above phenomena occur, the pH standard buffer solution cannot be continued. used.
