LC-MS as a Stability-Indicating Method for Analysis of Hyoscine N-Butyl Bromide under Stress Degradation Conditions with Identification of Degradation Products

Abstract

Hyoscine N-Butyl Bromide (HBB) was subjected to different ICH prescribed stress conditions. It showed extensive decomposition under base hydrolytic conditions, while it was less liable to stress acid hydrolytic conditions. It showed also moderate degradation in response to oxidation stress of hydrogen peroxide. The drug showed no changes under photolysis conditions. In total, a number of major degradation products were detected by HPLC and identified by LC-MS. For establishment of stability-indicating assay, the reaction solutions in which different degradation products were formed were prepared, and the separation was optimized by varying the HPLC conditions. An acceptable chromatograms was achieved using a C18 column using (water: methanol 50: 50 v/v, pH adjusted to 3.9 with triflouroacetic acid) as a mobile phase with flow rate of 1.0 ml min−1 and UV detection wavelength at 210 nm. The percent of degradation was calculated in each run by measuring the intensity of the peak area of the intact drug at 6.2 min. Complete degradation only occur in case of 5 N NaOH indicates that the drug is very sensitive to alkaline hydrolysis. The LC-MS study was carried out to identify the major degradation products using a sunfire (waters) C-18 column and a mobile phase comprising of acetonitrile: 0.1M ammonium acetate (80:20, v/v) with flow rate of 1.0 ml min−1. MS measurements were acquired in positive ion full scan modes from 50 to 400 amu. The m/z values of the main peaks were investigated with the expected chemical structure of degradates.