Potentiometric titration of base salts

HOW TO DETERMINE THE ACTIVE INGREDIENT CONTENT IN A DRUG WITH POTENTIOMETRIC TITRATION?


This method is largely used in drug control. 
  • In this sheet is addressed the potentiometric titration of lidocaine hydrochloride, an organic base halogenated salt. This titration is also called Billon method.
Principle of the titration:
  • This titration method has the advantage of being specific of the organic part, as it is the protonated base BH+ (that is to say the conjugated acid) that is tittered. The experiment takes place in ethanol, as most of the protonated bases are acid enough in that solvent to be tittered by sodium hydroxide. Potentiometric detection reveals the equivalence point. The volume of sodium hydroxide enables the calculation of the BH+ titer, and thereby that of the corresponding base.