How to Use the pH Meter and Precautions to Take
How to use a pH meter_How to use a pH meter (steps)
1. Open the back cover and insert a battery.
2. When installing the composite glass electrode, please note:
(1) The lower end of the composite electrode is a fragile glass bubble. Be careful when using and storing it to prevent it from colliding with other items.
(2) There is a KCl saturated solution in the composite electrode as the conductive medium. If the result of drying out is inaccurate, you must observe whether there is liquid at any time. If you find that there is a small amount left, go to the laboratory for perfusion.
(3) The interface of the composite electrode instrument must not be contaminated, including water droplets.
(4) The composite electrode connection cannot be pulled forcefully to prevent the line connector from breaking.
3. After turning on the power switch, set it to the pH measurement position.
4. Use a thermometer to measure the temperature of the PH6.86 standard solution, and then adjust the pH meter temperature compensation knob to the measured temperature value.
5. Rinse the composite electrode with deionized water and dry it with filter paper.
6. Pour 2~5ml of PH6.86 standard solution into a plastic beaker that has been washed with water and wiped dry. Wash the beaker and composite electrode and then pour them away. Then add 20ml of PH6.86 standard solution into the plastic beaker and insert the composite electrode. In the solution, use the instrument positioning knob to adjust to a reading of 6.86 until stable. The following two points should be noted:
(1) The positioning must be adjusted according to the PH6.86 standard.
(2) After adjustment, never move the positioning knob again.
7. Wash the composite electrode with deionized water, dry it with filter paper, measure the temperature of the PH4.00 solution with a thermometer, and adjust the temperature compensation knob of the instrument to the measured temperature value.
8. Pour 2 to 5 ml of the PH4.00 standard solution into another plastic beaker, wash the beaker and the composite electrode and pour them away, then add 20ml of the PH4.00 standard solution, and insert the composite electrode into the solution. After the reading is stable, use the slope knob. Adjust to PH4.00. It should be noted that after the slope button is adjusted, it must not be moved again.
9. Use a thermometer to measure the temperature of the liquid to be measured, and adjust the temperature compensation of the instrument to the measured temperature.
10. Insert the composite electrode into the solution to be measured and read the pH value, which is the pH value of the solution to be measured. The following two points should be noted:
(1) The temperature should not be too high during measurement. If the temperature exceeds 40℃ and the measurement result is inaccurate, it needs to be taken out in a beaker and slightly cooled.
(2) The composite electrode should avoid contact with organic matter. Once in contact or contaminated, clean it with absolute ethanol.
11. Note: The instrument must be calibrated before use, that is, the above 4 to 8 operations. If the instrument is not shut down, it can be measured continuously. Once it is shut down, it must be calibrated. But it must be calibrated once every 12 hours even if it is not turned off.
Precautions for using ph meter
1. Under normal circumstances, when the pH meter is used continuously, it needs to be calibrated once a day; generally the instrument does not need to be calibrated within 24 hours.
2. Before use, pull off the rubber sleeve on the upper end of the pH meter electrode to expose the upper hole.
3. The calibration buffer solution generally uses a solution with pH=6.86 for the first time, and a buffer close to the pH value of the measured solution for the second time. If the measured solution is acidic, the buffer should be pH=4.00; if the measured solution is acidic, the buffer solution should be pH=4.00; When the solution is alkaline, choose a buffer with pH=9.18.
4. During measurement, the lead wire of the electrode should remain stationary, otherwise the measurement will be unstable.
5. Do not soak the electrode in distilled water. If the electrode used in the pH meter is a new electrode or an electrode that has not been used for a long time, it must be soaked in distilled water for several hours before use, so that the asymmetric potential of the pH meter electrode can be reduced to a stable level, thereby reducing the electrode's resistance. Internal resistance.
6. When measuring the pH value of the pH meter, make sure that the bulb of the electrode completely enters the medium being measured, so that more accurate measurement results can be obtained.
7. When using the pH meter, remove the rubber stopper from the solution filling port of the reference electrode.
