Using an atomic force microscope, the adsorption of 4-(dimethylamino)pyridine and pyridine, in aqueous solution, onto trisodium citrate equilibrated gold has been monitored by the decrease in the electrostatic potential of the gold surface with time. Pronounced changes in the force-separation curves as a function of time were observed, with determined potential decreases in the range of 20-30 mV. The time dependent diffuse layer potentials changes have been attributed to the displacement of citrate ions on the gold surface by the more strongly adsorbing aromatic amines.