A small electrolysis device, that does electrolysis, splits the reactants, stores them in two different PRTIs, and dispenses the reactants via spark.

The bottom section is an always on electrolysis device, splitter and storage.  The top part of the device is the dispenser.  Just cause a spark on the PSCN in the upper section to dispense.  The upper PRTIs should be matched with respective PRTOs whereever you want the OXYG or HYGN to go.  In this save, a manual spark releases a gas particle into a small one particle storage area.