Sensitive and selective determination of picogram amounts of ciprofloxacin and its metabolites in biological samples using high-performance liquid chromatography and photothermal post-column derivatization.

An analytical method for the detection and quantification of ciprofloxacin and its known metabolites M1, M2, M3 and M4 in urine, serum/plasma, bile, faeces and tissue is described. For the liquid matrices the only sample preparation that is required is dilution. The assay consists of reversed-phase high-performance liquid chromatography and fluorescence detection. For the metabolites M2, M3 and M4 an additional post-column derivatization by successive thermolysis and photolysis is needed. A suitable simple post-column reactor has been constructed. Detection limits for all compounds are between 0.2 and 2.2 ng/ml (absolute detection limits 2-22 pg). Compared with fluorescence detection alone, the derivatization increases the selectivity of detection significantly. The linearity, precision and accuracy of the method were determined.