The quality of an analysis depends on the quality of the calibration. The quality of a calibration depends on attention to detail.

The quality of an analysis depends on the quality of the calibration. The quality of a calibration depends on attention to detail.

- Selection of calibration samples:

- number

- concentration ranges

- families - Preparation of calibration samples
- Choice of calibration function
- Precision during calibration
- Optimisation of calibration curve

In optical emission spectrometry a typical calibration function has the form:

where *C _{i}* is the content (or concentration) of element

The calibration function given here is linear (in its dependence on the
fitting parameters) and second order (the highest power of *I _{i}*).
Sometimes higher order functions or non-linear functions are used. Several
simplifications are also possible. If

To determine the best values for the fitting parameters it is usual to find
the minimum of a least-squares function:

where *w _{i}* are the weights given to each calibration point

Several parameters are available to determine the goodness of fit. Unweighted equations are shown here for simplicity though, of course, weighted functions should be used.