1.1 This test method covers the quantitative determination of ferrous oxide (FeO) by oxidation of ferrous iron (Fe⁺⁺) in an acid solution to the ferric state (Fe⁺⁺⁺) and titration with potassium dichromate using diphenylamine as the indicator.

1.2 This test method is applicable to synthetic black iron oxide, natural black iron oxide, magnetite or brown iron oxide where part of the iron content is present in the ferrous state (Note 1). It is applicable to iron oxides where the ferrous iron content ranges from 50 to 0.20 %.

Note 1 - Natural iron oxides and magnetite may contain traces of metallic iron that will be combined with and analyzed as FeO.

1.3 This standard does not purport to address the safety concerns if any, problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.