Determination of pharmaceutical compounds containing covalently-bound halogen by means of ion-selective electrodes

Organic compounds containing covalently bound halogen can be determined by potentiometric techniques with ion-selective electrodes in different ways. Apart from potentiometric titration of the halide after combustion, direct potentiometric determination of the halide produced at appropriate pH in the solution of the compound in the presence of silver(I) catalyst dissolved from the ion-selective electrode is possible in some cases. In the latter case, the chain length is critical; the chain must have at least three carbon atoms for hydrolysis to take place. Titration with a silver nitrate solution is also possible; prior pH adjustment is then needed for myelobromol but not for the other compounds tested.