I am currently using a colorimetric assay to determine total iron binding capacity using a kit. The kit uses 2 buffers one to obtain total iron and one to obtain the unsaturated iron. We are not using serum samples-it is a various forms of transferrin-apo, saturated.

I am not having success in generating any information at the required concentration of the assay which the replicates and experiments are very variable.

What are other assays available that may have a more accurate and precise functional measurement. We already use a radial immunodiffusion assay to quantify the protein-but we are having a difficult time determining if it is functional.