D1-differential potentiometric and proton NMR spectrometric determination of mexiletine hydrochloride and its pharmaceutical formulations.

Abstract

Abstract To determine mexiletine hydrochloride (I) by potentiometry, sample was dissolved in anhyd. acetic acid and mercuric acetate with stirring for 10 min. The mixture was titrated against 0.025N-perchloric acid while recording the first-derivative (D1) differential curve (.DELTA.E/.DELTA.V vs. V); the end-point coincided with the sharp peak at the maximum D1 value. For determination by 1H-NMR, a sample was mixed with maleic acid in DMSO-d6 and the spectra of a portion of the resulting soln. was recorded; measurement involved integration of the signals at 6.94 and 1.37 ppm. Both methods were applied to the determination of I in capsules and injection soln. Mean recoveries were 100.4 and 99.5% by D1-differential potentiometry and 1H-NMR, respectively. Results by both methods were comparable with those of official BP methods.