A method for removing ferric-ferrous oxides from a liquid containing ferric-ferrous oxides and ferrous ions and to a method for determining the amount of ferrous ion in a liquid. The invention has particular utility for use in a method to accurately determine the corrosion rates of ferrometals in contact with aqueous liquids by filtering ferric-ferrous oxides from the aqueous liquid prior to determining the ferrous ion content of the aqueous liquid.
