Search Results

You are looking at 1 - 2 of 2 items for

  • Author: Nasr Y. Khalil x
Clear All Modify Search
Open access

Ibrahim A. Darwish, Tanveer A. Wani, Nasr Y. Khalil and Hamdy M. Abdel-Rahman

Abstract

The study describes the development and validation of a new microwell-based spectrophotometric assay for determination of olmesartan medoxomil (OLM) in tablets. The formation of a colored charge-transfer (CT) complex between OLM as an n-electron donor and 2,3-dichloro- -5,6-dicyano-1,4-benzoquinone (DDQ) as a p-electron acceptor was investigated, and employed as the basis for the development of the new assay. The proposed assay was conducted in 96-microwell plates. The absorbance of the colored-CT complex was measured at 460 nm with a microplate reader. Optimum conditions of the reaction and the analytical procedures of the assay were established. Under the optimum conditions, a linear relationship with a good correlation coefficient was found between the absorbance and the concentration of OLM in the range of 2-200 μg per well. The limits of detection and quantitation were 0.53 and 1.61 μg per well, respectively. No interference was observed from the excipients present in OLM tablets or from hydrochlorothiazide and amlodipine besylate that were co-formulated with OLM in some of its formulations. The assay was successfully applied to the analysis of OLM in tablets with good accuracy and precision. The assay described herein has a great practical value in the routine analysis of OLM in quality control laboratories, since it has a high throughput property and consumes low volumes of organic solvent. It thus offers a reduction in the exposure of analysts to the toxic effects of organic solvents, as well as a reduction in the cost of analysis.

Open access

Amer M. Alanazi, Ali S. Abdelhameed, Nasr Y. Khalil, Azmat A. Khan and Ibrahim A. Darwish

Abstract

A simple, sensitive and accurate HPLC method with high throughput has been developed and validated for the simultaneous determination of irbesartan (IRB) and hydrochlorothiazide (HCT) in combined pharmaceutical dosage forms. The proposed method employed, for the first time, a monolithic column in the analysis. Optimal chromatographic separation of the analytes was achieved on Chromolith® Performance RP-18e column using a mobile phase consisting of phosphate buffer (pH 4)/acetonitrile (50:50, V/V) pumped isocratically at a flow rate of 1.0 mL min-1. The eluted analytes were monitored with a UV detector set at 270 nm. Under the optimum chromatographic conditions, linear relationship with a good correlation coefficient (R ≥ 0.9997) was found between the peak area and the corresponding concentrations of both IRB and HCT in the ranges of 10-200 and 1-20 ng mL-1. The limits of detection were 2.34 and 0.03 ng mL-1 for IRB and HCT, respectively. The intra- and inter-assay precisions were satisfactory as the RSD values did not exceed 3 %. The accuracy of the proposed method was > 97 %. The proposed method had high throughput as the analysis involved a simple procedure and a very short run- -time of < 3 min. The results demonstrated that the method is applicable in the quality control of combined pharmaceutical tablets containing IRB and HCT