Thermal analysis TGA/DTA was performed for the grafted and co-grafted gold NPs under O 2 to determine the mass of organic matter grafted to nanoparticles. Table shows the results of thermogravimetric analysis obtained with single and two diazonium-modified Au NPs. The mass of organic layer at high concentrations of diazonium salt AB is more than two salts (AB/DMB), while this trend is reverse for lower concentrations of AB/DMB and the mass of organic layer in these two salts is more than single salts AB. There is a clear reduction in the mass of organic matter from 10 -3 M to 510 -5 M diazonium salt concentrations, for both single and dual modifications. This decrease in the mass of organic matter occurs for single salts with a higher incidence than the use of salt mixtures.