A solution containing Cd2+ was analyzed voltammetrically using the standard addition method. Twenty-five milliliters of the deaerated solution, which was 1 M in HNO3, produced a net limiting current of 1.78 μA at a rotating mercury film working electrode at a potential of -0.85 V (versus SCE). Following addition of 5.00 mL of a 2.25 x 10-3 M standard Cd2+ solution, the resulting solution produced a current of 4.48 μA. Calculate the concentration of Cd2+ in the sample.