What is a standard buffer solution for a pH meter? What are the characteristics?
A pH buffer solution is a solution that keeps the pH stable. If a small amount of acid or base is added to this solution, or a small amount of acid or base is produced by a chemical reaction in the solution, as well as appropriate dilution of the solution, the pH value of this solution is basically stable and unchanged, this kind of solution that can counteract a small amount of acid or base or dilution, and make the pH value is not easy to change is known as pH buffer solution.
pH meter standard buffer solution has the following characteristics:
(1) the pH value of the standard solution is known and achieve the required accuracy;
(2) The pH value of the standard solution has good reproducibility and stability, with a larger buffer capacity, smaller dilution value and smaller temperature coefficient;
(3) The preparation of the solution is simple;
2, for PH meter, pH buffer solution is the main role?
(1) pH measurement before calibration calibration pH meter
(2) used to check the accuracy of the pH meter, for example, after calibrating the pH meter with pH 6.86 and pH 4.00, the pH electrode will be inserted into pH 9.18 solution to check whether the instrument display value and the pHs value of the standard solution are consistent;
(3) Check whether the pH meter needs to be recalibrated during general accuracy measurements. pH meters may perhaps drift or change after calibration and use, so insert the electrode into a standard buffer that is closer to the solution under test before testing, and determine whether it needs to be recalibrated based on the magnitude of the error.
(4) Test the performance of the pH electrode
3,How to prepare pH standard buffer solution?
For general pH measurements, you can use sets of pH buffer reagents (can be prepared 250ml), the preparation of the solution, you should use deionised water, and pre-boil for 15 to 30 minutes to remove dissolved carbon dioxide. Cut open the plastic bag and pour the reagent into a beaker, use appropriate amount of deionised water to make it dissolve and rinse the bag, then pour it into a 250ml volumetric flask, dilute it to the scale and shake it well.
4,How to keep and use pH buffer solution correctly.
Buffer solution preparation, should be installed in glass bottles or polyethylene bottles (alkaline pH buffer such as pH9.18, pH10.01, pH12.46, etc., should be installed in polyethylene bottles) cap tightly capped tightly in a refrigerator at low temperatures (5 ~ 10 ℃) preservation, generally can be used for about two months, such as turbidity, mildew or precipitation phenomena such as the discovery of can not be continued to use. When using, several 50ml polyethylene vials should be prepared, the buffer solution in the vial should be poured into the vials, and placed in the ambient temperature for 1~2 hours, and then used after the temperature is balanced. After use, it should not be poured back into the vial to avoid contamination. The buffer solution in the vial can be used for 2 to 3 days under the ambient condition of "10℃", and the three solutions of pH7.00, pH6.86 and pH4.00 can be used for a longer period of time, and the pH value of pH9.18 and pH10.01 solution can be changed more easily due to the absorption of CO2 in the air.
