1.1 This method is applicable to the determination of pH value of drinking water, surface water and industrial sewage.
1.2 The color, turbidity, colloidal matter, oxidizer, reducer and salt content will not disturb the determination; however, in the strongly acidic solution with pH less than 1, there will be so-called acid error, which can be determined according to the acidity; in alkaline solution with pH greater than 10, there is a great deal sodion in it, making the readings on the low side, which is generally called as sodium error. In order to eliminate sodium error, not only purpose-made low-sodium error electrode can be adopted, but also standard buffer solution with pH value similar to the tested solution can be adopted to correct the instruments.
The temperature may influence electric potential of the electrode and ionization equilibrium of the water. The temperature of the compensating device of the adjusting instruments must be the same as that of the solution, and the temperature error between the tested specimen and the standard buffer solution for calibrating instruments shall be within ±1℃.
1 Application Scope 2 Definitions * 3 Theory 4 Reagents 5 Instruments 6 Specimen Retention 7 Procedures 8 Precision (See Table 3) 9 Annotation 10 Test Report Additional Explanations:
1.1 This method is applicable to the determination of pH value of drinking water, surface water and industrial sewage.
1.2 The color, turbidity, colloidal matter, oxidizer, reducer and salt content will not disturb the determination; however, in the strongly acidic solution with pH less than 1, there will be so-called acid error, which can be determined according to the acidity; in alkaline solution with pH greater than 10, there is a great deal sodion in it, making the readings on the low side, which is generally called as sodium error. In order to eliminate sodium error, not only purpose-made low-sodium error electrode can be adopted, but also standard buffer solution with pH value similar to the tested solution can be adopted to correct the instruments.
The temperature may influence electric potential of the electrode and ionization equilibrium of the water. The temperature of the compensating device of the adjusting instruments must be the same as that of the solution, and the temperature error between the tested specimen and the standard buffer solution for calibrating instruments shall be within ±1℃.
Contents of GB/T 6920-1986
1 Application Scope
2 Definitions *
3 Theory
4 Reagents
5 Instruments
6 Specimen Retention
7 Procedures
8 Precision (See Table 3)
9 Annotation
10 Test Report
Additional Explanations:
