Calibrate a pH sensor

Improve the accuracy of pH measurements by calibrating the pH sensor.

Prepare the buffer solutions

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

Calibrate the sensor in the software after preparing buffer solutions.

1. Connect the sensor to Capstone.
2. Select Calibration from the Tools palette.
3. Select pH for the measurement, then click Next.
4. Select Two Standards (2 point) for the calibration type, then click Next.
5. Rinse the pH probe with distilled water and blot dry with a towel.
6. Place the probe in the lower pH buffer.
7. Enter the value of the pH buffer in Standard Value, then click Set Current Value to Standard Value.
8. Repeat Steps 5 to 7 using the higher pH buffer.
9. Review the calibration, then click Finish.

Note

For the Wireless pH Sensor, the calibration remains on the sensor. You can restore the factory calibration if needed. For all other pH sensors, the calibration remains on the Capstone file if saved.