Ion pair extraction titration

TITRATION OF LIDOCAINE HYDROCHLORIDE

Titration will be performed in the laboratory using:

A tittered DOSS solution of concentration: [c] = 0.0184 M, made up according to the European pharmacopoeia standards.
A test sample of lidocaine hydrochloride: 33.3 mg of raw material.
A theoretical expected volume of DOSS from the burette (assuming that the raw material is pure):

formula for the calculation of the expected theoretical volume of DOSS drop

(1)

N.A.: Letting n lidocaine be the number of moles of raw material involved in the titration, the following can be written:

Integration of this value in equation (1) gives:

theoretical drop volume of DOSS burette = 6.25 x 10 exp -3 L

Therefore, if the ascorbic acid raw material is pure, we obtain, with the concentrations of the reagents used in this assay, 6.25 mL iodine from the burette at the equivalence point.