DARU Journal of Pharmaceutical Sciences 2008. 16(4):256-262.

Indirect spectrofluorimetric determination of omeprazole by its quenching effect on the fluorescence of Tb3+-1,10-phenanthroline complex in presence of bis (2-ethylhexyl) sulfosuccinate sodium in caps
M Shaghaghi, J.L Manzoori, A Jouyban



Purpose: Omeprazole (OMZ) is a substituted benzimidazole, which is used in the treatment of gastric acid related disorders. The aim of this study was the development and validation of a rapid, simple and reliable fluorimetric method for determination of OMZ in pharmaceutical formulations based on fluorescence quenching of Tb3+-1, 10-phenanthroline complex.

Method: For the determination of OMZ, aliquots of Tb3+, bis (2-ethylhexyl) sulfosuccinate sodium (AOT), 1,10-phenanthroline (phen) solutions (in optimal concentrations), aliquots of working OMZ solution and Tris-HCl buffer (pH 7.0) solution were added to 5 mL volumetric flasks. The mixture was then diluted with distilled water and allowed to stand for 30 min and the fluorescence intensity was then measured at 545 nm using an excitation wavelength of 300 nm. Matrix systems of OMZ (OMZ capsules with a nominal of 20 mg) were prepared by powdering and mixing the contents of ten capsules of OMZ. A portion of 10.0 mg of this powder was then accurately weighed and dissolved in about 10 mL of 0.1 M NaOH solution and filtered into a 100 mL volumetric flask. The residue was washed several times with water and solution was diluted to the mark. A suitable aliquot of this solution was applied for fluorimetric determination of OMZ. The recovery assay was carried out using the same procedure by addition of known amounts of OMZ.

Results: It was found that the fluorescence intensity of Tb3+-1, 10-phenanthroline complex can be greatly quenched by omeprazole in the presence of AOT. Under optimal conditions, the quenched fluorescence intensity was found to be proportional to the concentration of omeprazole in the range of 0.05-10 µg/mL. The detection limit was 0.016 µg/mL. The relative standard deviation values for 6 replicated determinations of 0.3 and 1.5 µg/mL of OMZ were 3.5 and 1.5 %, respectively, The RSD of intraday was 2.6 and that of interday was 3.4 % for 4 and 2 µg/mL of OMZ, respectively.

Conclusion: Based on the obtained results, a simple, rapid and selective spectrofluorimetric method was developed for determination of omeprazole in its capsule formulations with excellent reproducibility and allowed the interference-free determination of OMZ in real samples.  


Sensitized fluorescence, Omeprazole, Terbium, Fluorescence quenching,

Full Text:



  • There are currently no refbacks.