Masking of Cu²⁺ can be achieved by reduction to Cu⁺.  A 25.00 mL aliquot of a solution containing Cu²⁺ and Ni²⁺ was treated with ascorbic acid at pH 3.0 to reduce the Cu²⁺ ions. The pH was adjusted to 10.0 and 27.32 mL of 0.0565 M EDTA was required to reach a murexide end point. In a parallel titration, 40.45 mL of 0.0565 M EDTA was required to reach the murexide end point in a 25.00 mL aliquot that was not treated with ascorbic acid.  What amounts of copper and nickel in ppt (mass/vol.) were in the original solution?