Fluorimetric assay of rufloxacin in serum and in pharmaceutical formulations

A simple and rapid fluorimetric method for the determination of 9-fluoro-10-[N-(4'-methyl)piperazinyl]-7-oxo-2,3-dihydro-7H-pyrido[1,2,3 - d,e][1-4]benzothyazin-6-carboxylic acid hydrochloride (MF 934), in serum and in pharmaceutical formulations, has been developed based on its strong fluorescence, in 0.1 N H2SO4, at 526 nm (excitation wavelength at 340 nm). The procedure which involves the direct dilution of the sample requires only a few minutes and the sample volume is only 20-100 microliters of serum, depending on the drug concentration. Tedious sample preparation procedures such as extraction, deproteinization, or centrifugation are not necessary. The minimum concentration that can be detected is 0.3 ng ml-1, the standard curve in 0.1 N H2SO4 was found to be linear from 0.005 to 1.5 micrograms ml-1 and from 0.01 to 0.07 g in plasma after dilution with 0.1 N H2SO4.