Carbonate ions also produce a white precipitate with barium chloride solution. The acid reacts with any carbonate ions present. This removes them, so stopping them giving a false positive result.

For the buffer layers, they considered using CdS as well as new alkaline earth metal chalcogenides such as magnesium sulfide (MgS), calcium sulfide (CaS), strontium sulfide (SrS), and barium ...

For this, small fabric squares were coated with a polymer layer before being repeatedly dipped in solutions containing calcium or barium ions, as well as carbonate or sulfate ions. This procedure ...