Determining the metal weight percent of gold nanoparticles coated with organic thin films can be effectively achieved using thermal gravimetric analysis (TGA). TGA involves the combustion of organic materials at high temperatures, around 1500 degrees Celsius, allowing for the gravimetric assessment of inorganic residues. The high purity of gold nanoparticles facilitates their recovery post-combustion. To ensure accurate results, washing the residue with polar organic solvents such as acetic acid, acetonitrile, or dimethyl formamide, followed by water, is recommended before drying the gold. For gravimetric analysis, it is essential to identify a suitable reactant for elemental gold, enabling direct weighing or dissolution in Aqua Regia (a mixture of hydrochloric and nitric acids) followed by a reaction with pyrophosphate for quantification.
