Serum, containing iron bound to transferrin (Tf) is placed in an acidic reagent containing vitamin C. At low pH, the iron is released from transferrin and. in the presence of vitamin C, is converted from the ferric (Fe3+) to the ferrous (Fe2+) form. This form then reacts with a colored substrate, reacts with a substrate (Ferrozine®), with the color change being detected at a specific wavelength.
