Sodium silicate and hexametaphosphate suspensions yielded similar iron fractograms (Figure ), with primary and secondary light scattering peaks. These peaks had maxima, based on 57 Fe intensity, at 34-35 and 44-45 minutes. Iron was also present in a broad peak, eluting between 15 and 30 minutes, that did not coincide with a significant light scattering signal but did adsorb UV light at 254 nm. This peak may represent iron nanoparticles that are too small to be quantified using the online MALS detector. In sodium hexametaphosphate suspensions, the principal 31 P peak eluted at approximately 14 minutes, which matches the peak retention of sodium hexametaphosphate in pure water (Figure ).