Using the pH Probe

Preparation of the pH Sensor

A pH sensor connected to a computer will be used to measure pH. Plug the pH probe into channel 1 of the interface box. Plug the power cord on the interface box into an electrical outlet.

Click on the photograph to view an enlargement.

Start Logger Pro by double-clicking the icon (if available) or clicking Programs - Vernier Software - Logger Pro.

The pH meter is displayed at the bottom left side of the screen. 

Checking and Using the pH Sensor

The probe tips age and occasionally need to be replaced, especially if they have become dry. Use the procedure described below to check your probe by measuring the pH of two different solutions that have a known pH. Inform your instructor if the pH differs by more than 0.5 units from the known pH. 

1.  The probe tips are kept in a storage solution to keep them moist and protect them. Unscrew the small bottle and rinse the probe with distilled water as shown in the photograph. Be sure to squirt water onto the tip of the probe as well as around the sides.

2. After the probe has been thoroughly rinsed, place the tip in a solution with a known pH of 3.0 or 4.0. The pH reading will be displayed on the computer screen in the area labeled "pH-Live." The reading will fluctuate for a short period of time. Slowly swirl the solution with the probe until the reading stabilizes.

The probe should be thoroughly rinsed each time it is moved from one solution to another. This can be done using a squeeze bottle containing distilled or deionized water.

3. Remove the probe from the solution, rinse it thoroughly by immersing it in a beaker of distilled water and swirling it. The probe should be kept submerged in the water when it is not used.

4. Transfer the probe to a solution with a known pH of 8.0 or 10.0. Slowly swirl the solution with the probe until the reading stabilizes.

4. When finished, rinse the sensor with distilled water before returning it to the pH electrode storage solution.