title: INVESTIGATION AND OPTIMIZATION OF TITRIMETRIC AND SPECTROPHOTOMETRIC METHODS FOR THE ASSAY OF FLUNARIZINE DIHYDROCHLORIDE USING IN SITU BROMINE.
abstract: Three indirect methods for the assay of flunarizine dihydrochloride (FNH) in bulk drug and commercial formulation based on titrimetric and spectrophotometric techniques using bromate-bromide mixture are described. In titrimetry, a measured excess of bromate-bromide mixture is added to an acidified solution of FNH and the unreacted bromine is determined iodometrically (method A). Spectrophotometry involves the addition of a known excess of bromate-bromide mixture to FNH in acid medium followed by estimation of unreacted bromine by its reaction with excess iodide and the liberated iodine (I₃⁻) is either measured at 370 nm (method B) or liberated iodine reacted with starch followed by the measurement of the blue colored starch-iodide complex at 575 run (method C). Titrimetric method is applicable over the range 4.5-30.0 mg FNH (method A), and the reaction stoichiometry is found to be 1:2 (FNH:KBrO₃). The spectrophotometric methods are applicable over the concentration ranges 0.8-16.0 µg/mL and 0.4-8.0 µg/mL FNH for method B and method C, respectively. The molar absorptivities are calculated to be 2.83 x 10⁴ and 4.96 x 10⁴ L mol⁻¹cm⁻¹ for method B and method C, respectively, and the corresponding Sandell sensitivity values are 0.0168 and 0.0096 µg cm⁻². The proposed methods have been applied successfully for the determination of FNH in pure form and in its dosage form and the results were compared with those of a literature method by applying the Student's t-test and F-test.
authors.forename: Kudige Nagaraj
authors.initials: KN
authors.lastname: Prashanth
authors.forename: Nagaraju
authors.initials: N
authors.lastname: Swamy
authors.forename: Kanakapura
authors.initials: K
authors.lastname: Basavaiah
mesh_terms: D001966:Bromine; D005444:Flunarizine / Q000032:analysis*; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D005444:Flunarizine; D001966:Bromine