Radioactive gold-198 nanoparticles have been synthesized using a green and chemically safe solvent, PEG 4000. In the present investigation, 198Au(III) has been quantitatively extracted by the PEG-rich phase without addition of any other extractant. Extraction is quantitative even at very high gold concentration (50 mM) and after extraction Au(III) is reduced to Au(0) forming radioactive gold nanoparticles. The PEG-rich phase containing radioactive gold nanoparticles has been characterized by UV-visible spectroscopy and the actual size has been determined using transmission electron microscopy (TEM).
