Calibrate a pH Sensor

Improve the accuracy of a pH sensor, such as the Wireless pH Sensor (PS-3204) or the PASPORT pH Sensor (PS-2102), by calibrating the pH measurement.

Prepare the buffer solutions

Before calibration, prepare two buffer solutions of different pH values to calibrate the pH sensor. You can create buffer solutions using the pH Buffer Capsule Kit (SC-2321), or by purchasing buffer solutions from a chemical supplier.

For best accuracy, use two pH buffers that are as close to the measured range as possible. For example, when measuring acids, use pH 4 and pH 7 buffers for calibration. When measuring both acids and bases, use pH 4 and pH 10 buffer solutions.

Set the calibration points

Once the buffer solutions are prepared, calibrate the sensor using the following procedure.

1. Connect the sensor to Chemvue.
2. From any page, select a Displayed Measurement button and select pH from the list of available measurements.

3. Select the same Displayed Measurement button again and select Calibrate from the menu.

   

4. In the Calibrate Measurement window, select Two Standards (2 point) from the dropdown list, then select Next.

   

5. Rinse the pH probe with distilled water and blot dry with a towel.

6. Place the probe into the lower pH buffer. Wait for the reading shown next to Sensor Value to stabilize.

7. Enter the known value of the lower pH buffer into the Standard Value box, then select Set Current Value to Standard Value.

   

8. Repeat steps 5 through 7 for the second calibration point using the higher pH buffer.

   

9. Review your new calibration, then select OK.

   

Note

For the Wireless pH Sensor (PS-3204), the calibration remains stored on the sensor even after it is disconnected. You can restore the factory calibration if needed.