Methods of producing an aqueous formulation of an antigen-binding protein or enhancing re-oxidation of an antigen-binding protein are disclosed. The methods comprise (a) contacting an aqueous solution comprising antigen-binding protein molecules with a charged depth filter under conditions sufficient to enhance re-oxidation of the antigen-binding protein molecules and achieve a decrease in the percentage of reduced antigen-binding protein molecules, compared to the percentage of reduced antigen-binding protein molecules observed prior to step (a); and (b) optionally, measuring the amount or relative amount of reduced antigen-binding protein molecules. Formulations comprising a re-oxidized antigen-binding protein are also described.