It is important that there is a connection between the event dated with ¹⁴C ('time of death') and the historic or environmental event wished to be dated. Thus short lived materials are preferred over long lived materials which may have a considerable own age.

Equally important the sample material should ideally be chosen such that the carbon originates directly from atmospheric CO₂. Hence terrestrial materials are preferred over marine materials.

For a guide on sample collection in Danish, please see here.