A New, Simple Colorimetric Method For Assaying Diosmin, And Flavonoids In Daflon Tablets And Orange Peel Extracts

A new colorimetric method for determination of diosmin is proposed. The method is based on formation of a chromophore by the flavonoid in presence of 75% (v/v) HCl showing maximum absorbance at 405 nm. The technique with linearity over 10 through 80μg flavonoid (r ± s.e. = 0.9994 ± 0.0008, b±s.e. = 0.0089 ± 0.0001, COV ± s.e. = 2.8 ± 0.5, n= 6 each) has been compared with standard aluminium chloride method and a modified version that utilizes aluminium chloride for primary complexation of the flavonoid, and then its determination by HCl method. The three techniques have been compared for determination of diosminequivalent flavonoid in Daflon tablets, assaying recovery of added diosmin to daflon extract, and determination of flavonoid in orange peel extracts. At approximately equi-normal concentrations perchloric and HCl were found most effective than sulfuric and nitric acids whereas o-phosphoric was least effective and glacial acetic acid ineffective in inducing the chromophore. Phenolics like phenol, hydroquinone, resorcinol, catechol, guaiacol, pyrogallol, gallic acid and tannic acid fail to develop color in absence or presence of glucose. This indicated that phenolic constituents and carbohydrate moiety in the flavonoid are not participating in the formation of chromophore. Key-words: Spectrophotometric assay, Flavonoid, Diosmin, Daflon, Orange peel.