Determination of soil pH glass electrode method (two)

Six, analysis and testing

(1) Instrument calibration

Insert the composite electrode and the temperature electrode into the standard buffer solution with a pH of 6.

(2) Determination of pH of soil water immersion

(1) Weigh 10g (accurate to 0.

(2) Insert the composite electrode and the temperature electrode into the sample suspension, gently turn the beaker to remove the water film of the electrode to promote rapid equilibrium, let it stand for a while, and record the pH when the reading is stable

Seven, calculation and presentation of results

When measuring pH with a composite pH electrode, the pH can be read directly without calculation

8.

The absolute difference between the repeated test results is allowed: the repeated test results of neutral and acidic soils shall not exceed 0.

Nine, matters needing attention

(1) The glass electrode that has not been stored for a long time needs to be soaked in water for 24 hours to activate it before it can be used

(2) Shaking the beaker during reading will cause the reading to be lower.

(3) Avoid the intrusion of acid and alkali vapors during operation

(4) The standard solution can generally be stored for 1 to 2 months at room temperature, and the shelf life can be extended in the refrigerator at 4°C

(5) Temperature affects the electrode potential and the ionization balance of water

(6) After every 5-6 samples are tested, the positioning should be checked with a standard solution

(7) The position of the electrode in the suspension has an influence on the measurement result.

(8) After continuously measuring samples with pH>7.

(9) During the process of adding water and stirring the sample and standing still, use plastic wrap to seal the mouth of the beaker to avoid contact with air and prevent carbon dioxide in the air from interfering with the measurement

(10) After each measurement, the electrode should be washed with distilled water immediately to prevent the sample solution from drying up on the surface of the electrode, especially when measuring samples containing more oil, emulsified solution and suspended solids

Related Links: Determination of Soil pH by Glass Electrode Method (1)