Black Iron Oxide Purity

Project Scope: A client in the recycling sector requested confirmation of black iron oxide purity to support material validation, documentation, and vendor approval with major industry customers. Black iron oxide (Fe₃O₄) contains iron in mixed oxidation states (Fe(II) and Fe(III)), with a theoretical iron content of approximately 72.4% in the pure state. To ensure an accurate, reliable determination of purity, multiple analytical methods with triplicate testing were used to provide a defensible result for client quality records.

Testing Performed

• Titration: Measured Fe(II) content at 22%, corresponding to 92% Fe₃O₄ using stoichiometric calculations.
• ICP-OES: Measured total Fe content at 67%, corresponding to 92% Fe₃O₄ using stoichiometric calculations.
• Methods Used:
  • Digestions: ASTM D6349 / EPA 3051A
  • Iron by Dichromate Titration Method: ASTM E394
  • Iron by Dichromate Titrimetry: ASTM E246
  • Ferrous Iron in Iron Oxides: ASTM D3872
  • Metals Determination by ICP-MS: ASTM D6357 by ICP-MS / EPA 6020B

Results and Impact

Both methods confirmed the material as 92% Fe₃O₄, consistent with high-purity black iron oxide. This clear, consistent confirmation enabled the client to:

• Confidently validate raw material quality.
• Maintain best-in-class vendor status with industry leaders.
• Accelerate shipment and use of recycled materials.

The project highlights how the judicious choice of complementary analytical methods can provide clear, defensible purity data, supporting confident decision-making for clients working to maintain quality and trust with their customers.