Tartrate as a substitute of citrate to prepare gold colloids from chloroauric acid

The citrate-reduction method is extensively used to prepare gold colloids particularly in the application of biological and medical areas. Tartrate as a substitute of citrate was first employed to prepare gold colloids from chloroauric acid due to its similar chemical structures to citrate. The size of obtained monodisperse quasispherical gold nanoparticles was adjusted from 27 nm to 40 nm when changing the molar ratio of sodium tartrate to chloroauric acid, while the particle size only changed from 54 to 62 nm under different molar ratio of tartaric acid to aurate. The nanoparticle size is mainly determined by the pH of reaction media in nucleation and the stabilizer concentration in the coagulation of initial nuclei for the nanoparticle growth. The majority of obtained gold nanoparticles have polycrystalline structure. This method should be important for direct one-pot preparation of gold colloids with sizes of around 30-60 nm.