The active ingredient in Antabuse, a drug used for the treatment of chronic alcoholism, is tetraethyl thiuram disulfide, (C2H5)2NCSSCN(C2H5)2 (296.54 g/mol). The sulfur in a 0.4169-g sample of an Antabuse preparation was oxidized to SO2, which was absorbed in H2O2 to give H2SO4. The acid was titrated with 19.25 mL of 0.04216 M base. Calculate the percentage of active ingredient in the preparation.