High Performance Liquid Chromatography (HPLC) Stability Indicating Method for the Determination of Bromazepam Via its Copper (II) Chelates

Assefa Takele1, Abdel-Maaboud I. Mohamed Attaya2, Ariaya Hymete3, Melisew Tadele Alula4, 5, *
1 Department of Chemistry & Pharmacy; Faculty of Science and Technology, University of Algarve, Faro, Portugal
2 Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt
3 Department of Pharmaceutical Chemistry, School of Pharmacy, Addis Ababa University, Addis Ababa, Ethiopia
4 Department of Chemical and Forensic Sciences; College of Science, Botswana International University of Science and Technology, Palapye, Botswana
5 Department of Chemistry; College of Science; Bahir Dar University, Bahir Dar, Ethiopia

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© 2017 Takele et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Chemical and Forensic Sciences; College of Science, Botswana International University of Science and Technology, Palapye, Plot 10071, Private Bag 16, Botswana; Tel: +26777424353; Fax: +267-4900102; E-mails:,



Bromazepam is hydrolyzed in acidic aqueous solution leading to a series of degradation products. The rate of acidic hydrolysis is believed to be dependent on the state of protonation of the pyridyl and azomethine nitrogen atoms. Stability test is important in pharmaceutical industry to provide evidence on how the quality of an active substance or pharmaceutical product varies with time under the influence of a variety of environmental factors.


The aim of the study was to develop a simple stability indicating method for the determination of bromazepam.


Bromazepam solution was prepared and forced degradation of bromazepam was performed under acid hydrolysis using sulphuric acid. High performance liquid chromatography determination of pure and degraded bromazepam and bromazepam-copper (II) complex was performed using reversed phase octyl C-8 column under isocratic conditions and the chromatographic conditions were set as follows; the flow rate of the mobile phase was 1.5 mL/min; injection volume was 10 μL, column temperature was 30oC and the detector wavelength being 309 nm.


Bromazepam, its degradation product and bromazepam chelated with copper (II) were determined using the developed mobile phase with flow rate of 1.5 mL/min. Good separation with sharp peak, minimum tailing and retention time repeatability was obtained. The rate order, rate constant and half-life of degradation were also determined, and it was observed that the degradation reaction follows the first order kinetics.


Chromatographic separation of bromazepam chelated with copper (II) was achieved and the method can be further used in drug manufacturing quality control.

Keywords: Bromazepam, HPLC, Method development, Stability, Anxiolytics, Kinetic study.