|Tropical Journal of Pharmaceutical Research|
|Official Journal of Pharmacotherpy Group|
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Novel colorimetric assay of mefenamic acid using 4-amino-3,5-dinitrobenzoic acid (ADBA)
SO Idowu†, SC Tambo, AO Adegoke and AA Olaniyi
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Ibadan, Ibadan.
Trop J Pharm Res, June 2002; 1(1): 15-22
Purpose: To develop a novel colorimetric assay method for mefenamic acid capsules.
Method: The new method (aromatic ring derivatization technique) is based on a diazo coupling reaction using diazotized 4-amino-3,5-dinitrobenzoic acid (ADBA) as a chromogenic derivatizing reagent.
Result: Optimization studies showed that the coupling reaction is very fast and completed in less than 1 minute. A 1:1 drug to reagent stoichiometric ratio was obtained for the azo dye formed. The azo adduct formed exhibits bathochromic shift with absorption maximum (lmax) at 490 nm, which was selected as the analytical wavelength. Lower limit of quantitation of mefenamic acid was 1 mg/ml. The assays were linear over the concentration range of 1 - 6 mg/ml and reproducible. This new method has been successfully applied in the assay of mefenamic acid capsules with accuracy similar to the official (B.P) titrimetric method of assay (p>0.05) and has the advantages of speed, high sensitivity, lower limit of detection and can be automated.
Conclusion: The method developed could find application in in-process quality control of mefenamic acid capsules.
Keywords: Mefenamic acid assay, 4-amino-3,5-dinitrobenzoic acid, colorimetry, diazotization.
†To whom correspondence should be addressed. E-mail: firstname.lastname@example.org Tel: +234 802 3094981
|@2002. TJPR Faculty of Pharmacy, University of Benin, Benin City, Nigeria|
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|Last updated: August 2002|