Warning: Copper and zinc salts are slightly to moderately toxic. Do not ingest them. Hydrochloric acid is corrosive.
You will need:
Ascorbic acid or sodium metabisulfite
Electrolytically oxidize the brass in sodium bicarbonate solution with a carbon cathode. Green copper carbonate and white zinc carbonate are formed. Filter and dissolve the precipitate in HCl. A dark green solution is formed. Add sodium bicarbonate until the pH of the solution is around 2 or 3. Then add ascorbic acid or sodium metabisulfite. White copper(I) chloride will precipitate. Filter. Now you have a copper(I) chloride precipitate and a zinc chloride solution. You have separated brass.