Ferrozine Assay for Simple and Cheap Iron Analysis of Silica-Coated Iron Oxide Nanoparticles

The Ferrozinen assay is applied as an accurate and rapid method to quantify the iron content of iron oxide nanoparticles (IONPs) and can be used in biological matrices. The addition of ascorbic aqcid accelerates the digestion process and can penetrate an IONP core within a mesoporous and solid silica shell. This new digestion protocol avoids the need for hydrofluoric acid to digest the surrounding silica shell and provides and accessible alternative to inductively coupled plasma methods. With the updated digestion protocol, the quantitative range of the Ferrozine assay is 1 - 14 ppm.