User Manual

Optical pH Sensors | User Manual

3.4 Second Calibration Point (basic pH)

It is highly recommended to perform a 2-point calibration before every measurement.

For pH Minisensor it is necessary to perform a 2-point calibration.

For the second calibration point, prepare a pH 11 solution based on the

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buffer capsule (item no. PHCAL11) or a custom calibration buffer.

Insert the pH and temperature sensor into the stirred buffer, and ensure that the sensor

tips are completely immersed in the water and free of air bubbles. Let the sensor

equilibrate (15 minutes for best result) and perform the calibration.

Wait for a stable sensor signal as this is substantial for correct pH measurements (this

can take several minutes depending on the temperature and stirring rate).

3.5 pH Offset Adjustment (Advanced Applications)

This will perform a pH offset adjustment to a buffer with exactly known pH value. The

pH of the solution has to be in the dynamic range of your sensor version (e.g. between

pH 6.5 – 7.5 for PK7 sensors). This can be used for measurements in highly complex

media (e.g. cell culture media) or for seawater measurements using a suitable reference

pH value (spectrophotometric pH measurement). Please contact PyroScience for support.

To undo the pH offset, please click on Delete calibrations in the calibration wizard. This

will delete all current calibration values and set the sensor back to factory calibration. A

2-point calibration has to be performed afterwards to start a measurement.

3.6 Common Warnings during Calibration

During the calibration various errors can occur, resulting in different warnings.

3.6.1 "Signal Intensity too low, refer to the manual”

The Sensor Signal Intensity can be too low for several reasons: