Determine Cu+2 and SO4-2 concentration using Potentiometry?
What is the range of the components? This is very important because this will determine if titration or photometry is used (or a combination of both). 

Also interfering components should be known. For eaxample. Barium is known to react with a lot of other components (solubility table). Also EDTA reacts with oter components (Also depending on the pH (EDTA complexation constants)

Titration:

Copper and sulfate can be determined in one analysis using and copper ISE. This is done by adding an NH3 buffer (pH of solution = 10) and adding an exxess of Barium nitrate. Barium will react with SO4 and the free barium is titrated. Titrate the solution with EDTA. This first inflection point will be copper, the second one the free barium.

Keep in mind that EDTA reacts with a lot of other components. Also if the concentration difference (molar) between copper and barium is large, high titrant usages are to be expected

Photometry:

Copper can be determined using an variaty of chemical substances (e.g. cuprizone, Bathocuproine). The choise depends on range, interfering components ect..

Sulfate is possible. However, titration is preferred.