Why are Na and NH4 ions not separated by precipitation with

Why are Na+ and NH4+ ions not separated by precipitation with the addition of an anion, like the other metal ions?

Na+ ion does not get precipitate out in presence of anion because the resulting sodium salts are soluble in water and so no precipitation occurs..On the other hand NH4+ is not metallic,it\'s a complex ion which consist of more than one elements and do not form any precipitation in presence of anion.