RP-HPLC Method for Content of Genotoxic 4-methoxybenzyl Chloride in Venlafaxine

Venlafaxine, primarily available in dosage in Venlafaxine hydrochloride (VEN∙HCl) form, is a discriminating serotonin and norepinephrine reuptake inhibitor (SNRI) anti-depressant drug. The 4-methoxybenzyl chloride (4-MBC) is a genotoxic impurity present in VEN∙HCl. A reverse-phase high-performance liquid chromatography (RP-HPLC) method is developed for the determination of 4-MBC content this method is validated employing ICH (International Council on Harmonisation) guidelines. During the method development, Purospher STAR end-capped (250mm x 4.0mm), 5µm HPLC column, and gradient profile for mobile phase with constant 1.0 mL/min flow rate are used. Mobile phase A is a buffer of pH 8.5 containing 0.1% v/v of liquid ammonia in water with adjusted pH using 10% orthophosphoric acid, whereas mobile phase B is acetonitrile. The injection volume, column oven temperature, and autosampler temperature were 50 µL, 55 °C, and 5 °C, respectively. The data is acquired at 225 nm wavelength. The method yields a well-separated peak of 4-MBC from Venlafaxine and its impurities. This method is linear in the range of LOQ to 150% level of specification concentration of impurity and the observed correlation coefficient is 0.999. The repeatability and intermediate precision are evaluated and the respective values of %RSD for 4-MBC content are 0.43 and 0.93. Robustness studies show insignificant change for the system suitability criteria like %RSD, theoretical plates, and tailing factor, their values being well within the acceptance limit. The new method for the quantification of genotoxic impurity 4-MBC is precise, sensitive, rugged, and accurate; it also qualifies all the criteria of stability, linearity, and robustness.