Extractional - Spectrophotometric Determination of Fenbendazole and Ornidazole in Pharmaceutical Formulations

Methods for spectrophotometric determination of fenbendazole and ornidazde are described. The methods are based on the formation and extraction of the ion-pair complex formed between bromothymol blue and either fenbendazole (FBZ) or ornidazole (ORN). The extracted coloured complexes absorb at 416 and 446 nm, respectively. The effect of different factors, e.g. pH, organic solvent, reagent concentration, extraction time, shaking time and common interfering species have been investigated. Fenbendazole and ornidazole can be determined over the range 1.2 to 24.0 ppm and 5.5 to 77.0 ppm, respectively. The precision of the methods was tested for the determination of pure samples of FBZ and ORN and the mean RSD was found to be 3.0 and 2.3% for FBZ and ORN, respectively.The proposed methods were successfully applied for the determination of FBZ and ORN in commercially dosage fornis. A comparison between the suggested methods and the other reported methods was also studied.