The chemical curve is the theoretical concentration curve based on nD and TEMP. It is defined by a set of 16 parameters.
| C00 | C01 | C02 | C03 |
| C10 | C11 | C12 | C13 |
| C20 | C21 | C22 | C23 |
| C30 | C31 | C32 | C33 |
A chemical curve is specific to the given process medium, for example, sucrose or sodium hydroxide. The set of parameters is given by Vaisala and should not be altered, except in case of changing to another process medium. The parameters can be changed by selecting 5 CALIBRATION from the Main menu, then, in the Calibration menu, 1 CHEMICAL & FIELD PARAMETERS, and finally 1 CHEMICAL CURVE PARAMETERS.