Determination of the antibacterial norfloxacin in human urine and serum samples by solid-phase spectrofluorimetry Original Research Article

A method for the determination of trace amounts of norfloxacin has been developed, based on solid-phase spectrofluorimetry. The relative fluorescence intensity (RFI) of norfloxacin fixed on Sephadex SP C-25 gel was measured directly after packing the gel beads in a 1 mm silica cell, using a solid-phase attachment. The wavelengths of excitation and emission were 272 and 446 nm, respectively. Using a sample volume of 1000 ml, the linear concentration range of application was 0.1–4.0 ng ml−1 of norfloxacin, with a relative standard deviation (R.S.D.) of 1.4% (for a level of 2.0 ng ml−1) and a detection limit of 0.04 ng ml−1. The method was applied to the determination of norfloxacin in human urine and serum samples. It was validated applying the standard addition methodology and using HPLC as a reference method. Recovery levels of the method reached 100% in all cases.