Colorimetric assay of propranolol tablets by derivatization: novel application of diazotized 4-amino-3,5-dinitrobenzoic acid (ADBA).
A novel colorimetric assay of propranolol tablets has been developed. The assay is based on chemical derivatization (aromatic ring derivatization technique) using diazotized 4-amino-3,5-dinitrobenzoic acid (ADBA) as the chromogenic derivatizing reagent and resultant formation of azo dyes. Optimization studies established an optimal reaction time of 5 min at 30 degrees C after mixing on a Vortex mixer the drug/reagent mixture for 10 s. A new absorption maximum (lambda(max)) was found at 470 nm, which was selected as the analytical wavelength. The assays were linear over 1-8 microg/mL propranolol, and the reaction occurred by a 1:1 reagent/drug stoichiometric ratio. The developed method has a low limit of detection of 0.76 microg/mL and is reproducible. It has been applied successfully to the assay of propranolol tablets and is of equivalent accuracy (p > 0.05) with the official (British Pharmacopoeia) ultraviolet spectrophotometric method. The new method has the main advantage of using more affordable instrumentation and could be applied to the in-process quality control of propranolol tablets.
University of Ibadan, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Orita UI, Ibadan-Oyo Rd, Nigeria. olakunleid@yahoo.com
Olakunle S
OS
Idowu
Olajire A
OA
Adegoke
Ajibola A
AA
Olaniyi
D000085:Acetates; D000319:Adrenergic beta-Antagonists / Q000032:analysis*; D002855:Chromatography, Thin Layer; D003124:Colorimetry; D004356:Drug Storage; D007202:Indicators and Reagents; D009579:Nitrobenzoates / Q000737:chemistry*; D011433:Propranolol / Q000032:analysis*; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets
D000085:Acetates; D000319:Adrenergic beta-Antagonists; D007202:Indicators and Reagents; D009579:Nitrobenzoates; D013607:Tablets; C007650:ethyl acetate; C484575:4-amino-3,5-dinitrobenzoic acid; D011433:Propranolol