Application of the Cloud Point Extraction Method in Spectrophotometric Estimation of Esomeprazole using Diazotised p-Nitroanline and Triton X -114

Abstract

A simple, sensitive, and precise spectrophotometric method has been developed for the quantification of esomeprazole as pure and in its dosage form (injection). The developed method is based on the diazo-coupling reaction of esomeprazole with a diazotized p-nitroaniline to produce a yellow azo dye soluble in an aqueous medium and gave a maximum absorption at 440 nm. Then using cloud point extraction method by adding Triton X-114 to azo dye solution and heating in water-bath at 50 0C for 25 minutes. The cloudy solution cooled in ice bath, then centrifuged for 20 minutes at 4000 rpm, separation the filtrate by decantation, and finally adding 1ml ethanol. The color of the product changed to pink color (redshift) and the pink-colored solution gave a maximum absorption at 585 nm. The optimization of the method conditions was investigated. Under the optimal conditions, Beer's law obeyed from 1 -20 µg/ml with determination coefficients (R2) equal to 0.9989 and an excellent value of molar absorptivity 1.9929 x 104 with a limit of detection (LOD) of 0.045µg/ml and limit of quantitation(LOQ) of 0.147 μg/ml. The developed method was successfully applied to the assay of esomeprazole in injection dosage with accepted analytical results.