2.1. The requirements of this standard will apply when it comes to the analysis of elements or compounds normally found in water. 2.2. However, in cases that require special precautions, the general procedure indicated in this standard will sometimes have to be altered. These special precautions will be indicated together with the prescriptions for the respective method of analysis. 23. The procedure varies depending on the origin of the water, its destination and the particular determinations requested by the interested parties.