Fluorescence reaction and complexation equilibria between norfloxacin and aluminium (III) ion in chloride medium |
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Authors: | Predrag T Djurdjevic Milena Jelikic-Stankov Dejan Stankov |
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Institution: | a Faculty of Science, University of Kragujevac, P.O. Box 60, 34000, Kragujevac, Yugoslavia b Faculty of Pharmacy, University of Belgrade, 11221, Belgrade, Yugoslavia c General Hospital “Dr. Dragisa Misovic”, 11000, Belgrade, Yugoslavia |
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Abstract: | Norfloxacin, 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid (NORH), reacts with aluminium(III) ion forming the strongly fluorescent complex Al(HNOR)]3+, in slightly acidic medium. The complex shows maximum emission at 440 nm with excitation at 320 nm. The fluorescence intensity is enhanced upon addition of 0.5% sodium dodecylsulphate. Fluorescence properties of the Al-NOR complex were used for the direct determination of trace amounts of NOR in serum. The linear dependence of fluorescence intensity on NOR concentration, at a NOR to Al concentration ratio of 1:10, was found in the concentration range 0.001–2 μg/ml NOR with a detection limit of 0.1 ng/ml. The ability of aluminium (III) ion to form complexes with NOR was investigated by titrations in 0.1 M LiCl medium, using a glass electrode, at 298 K, in the concentration range: 2 × 10−4 ≤ Al] ≤ 8 × 10−4; 5 × 10−4 ≤ NOR] ≤ 9 × 10−4 mol/dm3; 2.8 ≤ pH ≤ 8.3. The experimental data were explained by the following complexes and their respective stability constants, log(β ± σ): Al(HNOR)], (14.60 ± 0.05); Al(NOR)], (8.83 ± 0.08); A1(OH)3(NOR)], (−14.9 ± 0.1), as well as several pure hydrolytic complexes of A13+. The structure of the Al(HNOR)] complex is discussed, with respect to its fluorescence properties. |
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Keywords: | Fluorimetry Aluminium Potentiometry Norfloxacin |
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