Improved Colorimetric Determination of Reserpine in Tablets Using 4-Caboxyl-2,6-dintrobenzene diazonium ion (CDNBD)
Purpose: To develop a simple, rapid and improved colorimetric method for the assay of reserpine in tablets Method: The method is based on the aromatic ring coupling of reserpine with 4-carboxyl-2,6-dinitrobenzene diazonium ion with the consequent formation of an azo adduct. Optimization of reaction conditions and validation were carried out and the method applied to assay of reserpine in tablets. Result: Reserpine coupled readily with CDNBD and optimization of experimental conditions showed the reaction to be completed in 10 min at room temperature. A 1:1 drug to reagent stoichiometric ratio was obtained for the azo adduct formed. The adduct exhibited a bathochromic shift with respect to the drug and pronounced hyperchromic shift with respect to the reagent. Sample analyses were done using a colorimeter at 470 nm. The assays were linear and reproducible over the concentration range of 2.25 -24 µg/mL. The new method was successfully applied in the assay of reserpine in tablets with a performance similar to the official (USP) spectrophotometric method (p > 0.05). This method represents a profound improvement on the previously reported colorimetric method for reserpine. Conclusion: The method developed is rapid and could find application in in-process quality control of reserpine.
Keywords: Reserpine, colorimetry, 4-Caboxyl-2,6-dintrobenzene diazonium ion (CDNBD), diazo coupling
> Tropical Journal of Pharmaceutical Research Vol. 6 (2) 2007: pp. 695-703
Submission of a manuscript to this journal is a representation that the manuscript has not been published previously and is not under consideration for publication elsewhere.
All authors named in each manuscript would be required to sign a form (to be supplied by the Editor) so that they may retain their copyright in the article but to assign to us (the Publishers) and its licensees in perpetuity, in all forms, formats and media (whether known or created in the future) to (i) publish, reproduce, distribute, display and store the contribution, (ii) translate the contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or abstracts of the contribution, (iii) create any other derivative works(s) based on the contribution, (iv) to exploit all subsidiary rights in the contribution, (v) the inclusion of electronic links from the contribution to third party material where-ever it may be located, and (vi) license any thrid party to do any or all of the above.