Chemistry
pH probe Calibration
Calibrating a pH Sensor
For many experiments, calibrating a Vernier Go Direct pH Sensor is not required. A calibration equation is stored on each pH Sensor before it is shipped, which is used as a default by Vernier software. For the most accurate measurements with this sensor, we recommend calibration.
Depending on which pH sensor you have there is a slightly different software workflow. However it is a simple process that takes only a few minutes.

To calibrate the Go Direct sensor in Graphical Analysis, complete the following steps.
1. Click or tap the sensor meter to view sensor options.
2. Select Calibrate and follow the applicable prompts on the Calibrate Sensor screen.
3. Prepare the sensor for the first point, remove the storage bottle from the electrode (if applicable), rinse the tip of the sensor with distilled water, and place the sensor in the first standard solution so the tip is immersed.
4. Enter the known standard solution value for Reading 1.
5. When the voltage reading stabilises, tap Keep.
6. Prepare the sensor for the second calibration point,rinse the sensor with distilled water and place it in the second standard solution.
7. Enter the known standard solution value for Reading 2.
8. (Optional) If you wish to store the calibration on the sensor itself so that it remembers it the next time it is connected, tap the Storage tab at the top of the screen. If you wish to use the calibration only for the current experiment, skip to Step 9. On the Storage page, tap Save Calibration to Sensor. A message will appear: “Saving this calibration to the sensor will result in it being the new Custom Calibration 1.” Tap OK to proceed.
9. Tap OK to complete the calibration process.
In order to calibrate a pH Sensor, or to confirm that a saved pH calibration is accurate, you should have a supply of pH buffer solutions that cover the range of the pH values you will be measuring. For more information about pH buffer solutions
Once you have calibrated your Go Direct pH Sensor, the calibration is automatically stored to the sensor and will be used each time you connect to your device. You can always choose to restore factory defaults if you feel the custom calibration is invalid.
To restore factory defaults in Graphical Analysis, complete the following steps.
- Click or tap the live readouts meter and choose Calibrate.
- Click or tap Reset Calibration.
- A window will appear warning you that you are about to reset the calibration. Choose Reset Calibration.
To calibrate a pH sensor via a Labquest interface, complete the following steps.
1. Connect the sensor to LabQuest. The sensor reading will be displayed
2. Choose Calibrate from the Sensors menu and tap Calibrate Now
3. Prepare the sensor for the first point, remove the storage bottle from the electrode (if applicable), rinse the tip of the sensor with distilled water, and place the sensor in the first standard solution so the tip is immersed.
4. Enter the known value of the standard solution for the Reading 1.
5. When the voltage reading stabilises, tap Keep.
6. Prepare the sensor for the second calibration point rinse the sensor with distilled water and place it in the second standard solution.
7. Enter the known standard solution value for Reading 2.
8. When the voltage reading stabilises, tap Keep.
9. (Optional) If you wish to store the calibration on the sensor itself so that it remembers it the next time it is connected, tap the Storage tab at the top of the screen. If you wish to use the calibration only for the current experiment, skip to Step 9. On the Storage page, tap Save Calibration to Sensor. A message will appear: “Saving this calibration to the sensor will result in it being the new Custom Calibration 1.” Tap OK to proceed.
10. Tap OK to complete the calibration process.
In order to calibrate a pH Sensor, or to confirm that a saved pH calibration is accurate, you should have a supply of pH buffer solutions that cover the range of the pH values you will be measuring. For more information about pH buffer solutions
Once you have calibrated your pH Sensor, the calibration is automatically stored to the sensor and will be used each time you connect to your device. You can always choose to restore factory defaults if you feel the custom calibration is invalid.
To restore factory defaults on the Labquest interface, complete the following steps.
- Choose Calibrate from the Sensors menu
- Tap the Storage tab.
- Tap Restore Sensor Factory Defaults.