What is the one-point calibration of a pH meter?
Any pH meter must be calibrated with a pH standard solution before measuring the pH value of the sample. For samples with a measurement accuracy below 0.1 pH, a calibration method can be used to adjust the instrument. Generally, pH 6.86 or pH 7.00 standard buffer solution is selected. Some instruments only have a pH of 0.2 or 0.1, so they only have one positioning adjustment knob. The specific operating steps are as follows:
Measure the temperature of the standard buffer solution, check the table to determine the pH value at that temperature, and adjust the temperature adjustment knob to that temperature.
Rinse the electrode with pure water and shake dry.
Immerse the electrode in the buffer solution and shake it before standing still. After the reading is stable, adjust the positioning knob to make the instrument display the pH value of the standard solution.
Remove the electrode, rinse and shake dry.
Measure the temperature of the sample and adjust the pH meter temperature compensation knob to that temperature value.
Immerse the electrode in the sample solution, shake it and let it stand still. After the display stabilizes, take a reading.
How to clean pH electrodes?
After the bubble and liquid interface are contaminated, first clean with the following solvents, then rinse with deionized water to remove the solvents, and immerse the electrode in the soaking solution for activation.
(1) Pollutants: inorganic metal oxides, organic oils and fats, resin polymers, protein and blood cell precipitates, pigment substances, etc.
(2) Cleaning agents: Dilute acid below 1mol/L, dilute detergent (weakly acidic), dilute alcohol, acetone, ether, acidic enzyme solution (raw tablets), dilute bleach, hydrogen peroxide, etc.
