Patent ID: 8779011

Claim:
A method for preparing an ultrapure colloidal silica dispersion, comprising the steps of: dissolving a fumed silica in an aqueous solvent comprising an alkali metal hydroxide to produce an alkaline silicate solution; removing the alkali metal via ion exchange to generate a silicic acid solution; and adjusting temperature, concentration and pH of said silicic acid solution to values sufficient to initiate nucleation and particle growth; and cooling said silicic acid solution at a rate sufficient to produce said colloidal silica dispersion, wherein said colloidal silica dispersion has less than 200 ppb of each trace metal impurity disposed therein, excluding potassium and sodium, wherein said trace metal is selected from the group consisting of Fe, Al, Li, Rb, Cs, Fr, or any combinations thereof, and wherein said colloidal silica dispersion has less than 2 ppm residual alcohol.