CN-0428 conductivity calibration

Hi,

Currently I am using the EVAL-CN0428-EBZ water sensor in combination with this conductivity probe to measure the conductivity of a solution. I followed this guide to set it up which showed how to prompt the board with a serial connection. The issue I'm having is that the sensor is measuring around 1440uS in a 1413uS solution as shown in the picture below :

  

Another sensor I am using is correctly measuring around 1413uS. I tried cleaning the sensor and rinsing it with distilled water, but it did not help.

Is this behavior normal, or is there a way to calibrate it to be more accurate? I have looked through the wiki and the source code but I could not find any way to calibrate the sensor. There are also no commands provided to calibrate.

Best regards,

Bart