Buchi DuMaster D-480, Operation Manual, Page: 52 / 354

Operating instructions DuMaster D-480 ©BÜCHI Labortechnik AG
4 - Understanding the instrument and planning its use 52
Calibration curve calculation method criteria
Calibration curve configuration options
The user can specify the calibration curve calculation method according to the following criteria:

Calibration can be performed over the whole measuring range either consistently or in two
ranges.

For a specific element content you can set a dividing line for two calibration ranges.

For each range, you select a polynomial degree according to which to compute the calibration
curve (linear to 4th degree).
Calculation criteria
Look to the calibration view of the combi view for calibration curve calculation method criteria. You get
to the calibration view after performing or loading a series of defined calibration samples by selecting
Calibration > Calibrate...
and then the "Configuration calibration" dialog.
Ideal calculation method
If possible, try to compute calibration curves so that they

are uniform over the whole measuring range and/or concentration range

and can be displayed in linear form or on the basis of a polynomial of the lowest order.
To facilitate selecting a calculation method, four typical calibration graphs are shown below along with
the suitable calculation method.
Note:
For better understanding the calibration graphics are shown in a simplyfied way.
Linear calculation over the whole range
The following picture shows an example in which a linear calculation over the whole range achieves
acceptable calibration curve quality.