pH Meter

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Our pH meter is the Thermo Scientific Orion Lab Star PH111 pH/mV bench meter.

ThermoFisher provides a good video for calibration:

Calibration

Don’t break the electrode

Be sure electrode is ALWAYS in liquid. Dont let it dry out!

Calibrate frequently for best results.

Materials

Protocol

  1. Remove storage bottle from electrode.
  2. Rinse electrode with distilled water to remove any salt precipitate. Blot gently with kimwipe to remove excess water.
  3. Ensure electrode is filled enough. If not, refill with filling solution (3M KCl) into fill hole.
  4. Press the “Cal” key to start the calibration.
  5. Rinse the pH electrode with with buffer and then place into the ph buffer.
    1. Buffers can be done in any order.
    2. Ensure buffers are the same temperature as the sample to be measured.
  6. Wait for the pH value to stabilize.
    1. When the reading is stable, the checkmark icon is shown, and the reading is solid.
  7. Once the reading is stable, accept or edit the displayed pH buffer value. Press the “Enter” key to accept.
  8. Repeat steps 5-7 for the next calibration buffers.
  9. To save and end the calibration, press the “Cal” key.
  10. The meter will display the calculated slope value and then proceed to the main measure mode.

Measure pH

  1. Calibrate before measuring.
  2. Rinse electrode with distilled water. Blot gently with kimwipe to remove excess water.
  3. Place the electrode into the sample, submerging the measurement sensor and reference junction.
  4. Allow time for the reading to stabilize.
    1. The meter displays the stopwatch icon while the reading is stabilizing.
    2. The meter displays the checkmark icon when the reading is stable.
  5. Note the displayed measurements.
  6. Remove electrode from sample.
  7. Repeat steps 2-6 for all samples.

Storage

Short-Term Storage (up to one week)- Soak the electrode in the pH electrode storage solution. Cover the fill hole.

Long term storage (1+ week)- Rinse off any salt buildups with distilled water and remove any membrane/junction deposits. Fill the chamber with filling solution and securely cover the fill hole. Fill storage bottle with pH electrode storage solution and insert the electrode into the storage bottle.