How to perform a calibration
Selection criteria:
1- Linear range of the instrument if known: the range of concentrations for the calibration should preferably be within this linear range to ensure that a calibration curve can be plotted (see figure)
2- Range of concentrations of the compound to be dosed in the sample: ideally it should be towards the middle of the standard range.
If the concentration of the compound in the sample is outside of the concentration range of the calibration, the measurement of the sample will not be reliable: therefore, either dilute the sample for re-analysis or repeat the calibration interval