Plasma total iron-binding capacity measured by electron spin resonance

Electron spin resonance (ESR) is able to distinguish valence states of iron and between paramagnetic iron atoms in different molecular environments. Ferric ions attached to the carrier protein transferrin give a characteristic signal at g approximately 4.2, which is distinguishable from other signals in the blood. For this reason a test based on the increase in size of the iron transferrin signal should yield a fairly accurate measurement of the plasma total iron-binding capacity. Such a test would be much faster than most current methods.