Determination of Norfloxacin in Food by Capillary Electrophoresis Immunoassay with Laser-Induced Fluorescence Detector
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Determination of Norfloxacin in Food by Capillary Electrophoresis Immunoassay with Laser-Induced Fluorescence Detector Cuicui Liu & Xue Feng & Hailong Qian & Guozhen Fang & Shuo Wang
Received: 12 April 2014 / Accepted: 3 July 2014 / Published online: 15 July 2014 # Springer Science+Business Media New York 2014
Abstract A simple and sensitive capillary electrophoresis immunoassay method with laser-induced fluorescence detector was developed for the determination of norfloxacin in food samples. The assay was based on the competitive immunoreaction between fluorescein isothiocyanate-labeled norfloxacin tracer and free norfloxacin with a limited amount of antinorfloxacin antibody. In this study, the experimental parameters affecting the norfloxacin determination were systematically optimized including incubation time, buffer pH and concentration, and separation voltage. Under the optimal conditions, norfloxacin could be accurately quantified within 3 min using Na2B4O7/NaH2PO4 buffer (30 mmol/L, pH 8.0) for background electrolyte and 25 kV for the separation voltage. The linear range of the method was 0.08–50 μg/L with a detection limit of 0.005 μg/L. The relative standard deviations for migration time and peak area of the immunocomplex were 0.17 % (intraday) and 3.46 % (intraday), respectively. The proposed method has been further applied to the determination of norfloxacin in milk, chicken, pork, and fish samples, exhibiting satisfactory recovery and sensitivity. These results indicated that the proposed method might serve as an efficient tool for the selective determination of norfloxacin in food samples. Keywords Capillary electrophoresis . Competitive immunoassay . Laser-induced fluorescence . Norfloxacin
C. Liu and X. Feng contributed equally to this work. C. Liu : X. Feng : H. Qian : G. Fang : S. Wang (*) Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China e-mail: [email protected]
Introduction Norfloxacin [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1piperazinyl)-3-quinolone-carboxylic acid] belongs to the second generation of fluoroquinolone antibacterials, which shows striking potency against many pathogenic Gramnegative and Gram-positive bacteria by the inhibition of different kinds of enzymes (Lim et al. 2002; Sharma et al. 2009). In the last several years, norfloxacin has been ranked as the second-most-prescribed fluoroquinolone antibacterial just next to levofloxacin in China, and it has been widely used in both human and veterinary medicines for the treatment of gonococcal urethritis, respiratory and skin infections (Hernández-Arteseros et al. 2002; Chen et al. 2006; Goyal et al. 2012). The broad use of norfloxacin in animals may result in residues in animal-derived foods and subsequently leads to a public health hazard. Thus, developing highly specific and sensitive method for rapid determination of norfloxacin in food samples is of great importance. Recently, the methods
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