Another factor with Rodinal would be the tests show what's in the developer once matured, rather than the chemistry used to make it.

So the early Andresen published formula and both R09 & modern Rodinal would show Sulphite while in fact the first uses Metabisulphite and wouldn't test for the full hydroxide content that would need to be added.

Again it would be almost impossible to determine what form the p-Aminophenol was in when added.

Ian