In sop for pH meter, we will discuss the operation, calibration cleaning, and maintenance of pH meter.
pH meter SOP is developed to ensure that the Hanna pH Meter is working properly.
SOP for pH meter applicable for measuring pH in Quality Control Department.
Quality Control Manager
4. Operating Instructions of Hanna pH Meter
- Place the instrument on a flat surface and protect it against intense light and heat.
- Turn the instrument on by pressing the ON/OFF switch located on the rear panel.
- All LCD segments are displayed while the instrument performs a self-test.
- Make sure the electrode and the instrument have been calibrated together before taking pH measurements.
- Submerge the electrode and the temperature probe approximately 4 cm (1½”) into the Sample to be tested and stir gently. Allow time for the electrode to stabilize.
- The pH is displayed on the primary LCD and the temperature on the secondary LCD.
5. Precautions of using Hanna pH Meter
- The adapters supplied with the instruments should be used only with this instrument.
- The electrode should be kept for a long time in a 3M KCl solution.
6. Cleaning and maintenance of Hanna pH Meter
- The instruments must be cleaned only with a dust-free cloth slightly damped with detergent and methanol.
- The only maintenance is the replacement of batteries located on the backside of the instrument.
7. Why and when to Calibrate
- Calibration determines the current values of the asymmetry and slope of the electrode and they are stored in the instrument.
- Always calibrate after connecting another electrode.
- The instrument should be calibrated if upon connection and immersing in the WTW buffer it shows a deviation in value.
- Even if no deviation is observed ever, it should be calibrated fortnightly.
- AutoCal TEC is specially designed for technical buffer solutions as a fully automatic two-point calibration. The buffer solutions are automatically recognized by the instrument.
8. Calibration Procedure of Hanna pH Meter
1. Calibration has a choice of two memorized buffers: pH 4.01, 7.01,
2. Submerge the pH electrode and the temperature probe approximately 4 cm (1½”) into a buffer solution and stir gently. The temperature probe should be close to the pH electrode.
3. Press CAL. The “CAL” and “ ” messages will appear and the “7.01” buffer will be displayed on the secondary LCD. The “ ” symbol will blink on the LCD until the reading is stable.
4. When the reading is stable and close to the selected buffer, the “READY” message will appear and the “CFM” message will blink.
5. Press CFM to confirm calibration.
6. The calibrated value is then displayed as the primary LCD and the secondary LCD the second expected buffer value.
7. After the first calibration point is confirmed, immerse the pH electrode and the temperature probe approximately 4 cm (1½”) into the second buffer solution and stir gently. The temperature probe should be close to the pH electrode.
8. The “ ” symbol will blink on the LCD until the reading is stable.
9. When the reading is stable, the “READY” message will appear and the “CFM” message will blink.
10. Press CFM to confirm calibration. The instrument will return to measurement mode.
9. Evaluation of Calibration
After the calibration, the instrument automatically evaluates the current status. The asymmetry and slope are separately evaluated.