A Simple Kinetic Spectrophotometric Method For The Determination of Certain 4-Quinolones in Drug Formulations.

An accurate simple and selective kinetic procedure for the determination of certain 4-quinolones namely, norfloxacin (I), ofloxacin (II), enrofloxacin (III), fleroxacin (IV), ciprofloxacin (V) and pefloxacin (VI) is described. The procedure is based on reacting the studied compounds in acidic media (0.1 M HCL) with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in presence of cerium (IV) ammonium sulphate as an oxidant at room temperature for a fixed time of 20 min. for (I), (III), 12 min for (II) and 30 min for IV , V and VI, then the absorbance of the reaction product is measured at 630 nm. The concentration of the studied compounds is computed using the corresponding calibration curve equation for the fixed-time method. The absorbance-concentrations plot is rectilinear over the range 20-100 ug.ml^-1 for (I), 2 - 20 ug.ml^-1 for (II), 10 - 74 ug.ml^-1 for (III), 10 - 60 ug.ml^-1 for IV, 10 - 50 ug.ml^-1 for IV and 8 - 40 ug.ml^-1 for VI. The determination of the studied compounds by the fixed-concentration and rate constant methods is feasible with the calibration equation obtained, but the fixed-time method proved to be more applicable. The procedure was applied successfully to commercial tablets and ampoules and the results obtained were compared statistically with the reference methods.