ISO 2599:2003 specifies a titrimetric method for the determination of the phosphorus content of iron ores, using hexaammonium heptamolybdate (ammonium molybdate).

This method is applicable to a concentration range of 0,10 % (m/m) to 5,0 % (m/m) of phosphorus in natural iron ores, and iron ore concentrates and agglomerates including sinter products.

This International Standard provides a quality control method for the determination of phosphorus by titration, however, the method cannot be used for referee purposes.