While there are different types of pH electrodes, and many types of meters, the general calibration steps remain the same.
This is a VERY GENERAL outline of how to calibrate a pH electrode. Always reference the manual for procedures specific to your electrode and meter.
- Check that your electrode has been stored properly and that the pH bulb and junction are hydrated.
- Has the electrode been stored in HI70300L storage solution? If the electrode is dry, have it rehydrate for at least 1 hr in storage solution before attempting to calibrate it.
- Remove your electrode from the storage solution and rinse the electrode with deionized (DI) water.
- Rinsing the electrode with deionized water removes any salts, deposits, or impurities that may be clinging to the electrode glass.
- Don't have DI water? RO, distilled, pure, or demi water will work in a pinch!
- Use fresh buffers for your calibration.
- Select fresh buffers that bracket your calibration range. For example, if your sample is typically around pH 8.0, you will want to calibrate to at least 2 points ie. pH 7.01 and 10.01.
- If your electrode is refillable, open the fill cap.
- Ensure that the electrolyte level is at least 1 cm below the fill hole. If not, top-off the internal electrolyte.
- Pour your buffers into a clean beakers and put a stir bar into the beaker, and set it stirring on a magnetic stirrer.
- If you are using a sachet, you can swirl the electrode carefully around in the sachet.
- Turn on your meter and access calibration mode.
- Submerge the electrode in the buffer, and make sure the junction is covered.
- Allow the reading to stabilize. Some meters will automatically accept the calibration when the reading is stable, others you have to press a button to accept it.
- Once that buffer is accepted, remove the electrode from the buffer.
- Rinse the electrode with DI water before moving onto the next buffer.
- Repeat the rinsing, submerging, waiting to stabilize, and rinsing, until you have calibrated to all of the calibration points you need.
- Ensure the calibration is saved, and exit calibration mode.
- Rinse the electrode one more time.
- You're ready to test!
Some videos that demonstrate calibration procedures are: