How to do a calibration?
What is the aim of the experiment?
To establish the existing relation between the result of a measurement and the quantity (or concentration).

Many types of calibration according to the measurement method: external, internal, standard additions. This sheet will present external calibration in further detail.
What is its purpose?
To estimate a target compound (molecule/ion/atom)’s quantity (or concentration) in a sample.
Practical constraints
To dispose of a standard (target compound in the case of external calibration or standard additions, similar compound if internal calibration).
To have access to a measuring instrument (spectrophotometer, HPLC-UV, other according to the intended analysis).
To be in the linearity field of the instrument if possible.