Is there a method to separate ions from water other than by double displacement precipitation?

I'm working on a problem for school where we have to detect Fe3+, Ca2+, Cl-, and SO42- ions in water, and we have been given AgNO3, KSCN, BaCl2, and a HC2H3O2/Na2C2O4 mixture (all in solution) to do so. We have already determined the ion content by precipitating them out using successive double displacement reactions, but we also have to do it using another method. Is there another way to separate or detect ions in solution?


