Bromatometric Estimation of Levofloxacin HCI, Lomefloxacin HCI and Sparfloxacin in Bulk and Dosage Forms

Three simple and sensitive spectrophotometric methods are described for determination of levofloxacin HCl, lomefloxacin HCl and sparfloxacin in bulk and pharmaceutical dosage forms using bromate-bromide as the oxidimetric reagent. Drugs are treated with known excess of insitu generated bromine and residual unreacted bromine is determined by treating with fixed amount of either methylene blue, methyl orange or thymol blue then measuring absorbances at 678 nm, 510 nm 545 nm, respectively. The amount of bromine reacted corresponds to the amount of each drug. Beer's law was obeyed in the range of 0.05-1.0 μg.ml^-1 for levofloxacin HCl and lomefloxacin HCl and 0.1-1.4 μg.ml^-1 for sparfloxacin in case of methylene blue, of 0.1-1.0 μg.ml^-1 for levofloxacin HCl and lomefloxacin HCl and 0.1-1.8 μg.ml^-1 for sparfloxacin in case of methyl orange and of 0.25-2.75 μg.ml^-1 for levofloxacin HCl and lomefloxacin HCl and 1.0-5.5 μg.ml^-1 for sparfloxacin in case of thymol blue. Various analytical parameters have been evaluated such as effect of acidity, bromate - bromide volume and time, on the absorption and the results were validated according to ICH guidelines. The methods were satisfactory applied for the determination of drugs in both bulk and pharmaceutical forms and results were compared statistically with reference methods.