Quinolone is a family of widely prescript antibiotics in veterinary medicine. Their excessive use can be causative of quinolone residues in foodstuffs of animal origin. Therefore, a magneto immunofluorescence assay in microwell plate has been developed and validated to screen quinolone in bovine milk. The assay is based on an indirect competitive method where the quinolone in the milk sample competed with the quinolone immobilized on magnetic beads for the anti-quinolone antibody. Then, an anti-IgG antibody–labeled peroxidase and their respective substrates were added and the fluorescent signal was indirectly related with the quinolone concentration. Recoveries of quinolones from 82 to 102% were obtained in skimmed, whole, and raw milk samples in concordance with the results obtained by a reference method. Seven quinolones were evaluated quantitatively by the method, obtaining limits of detection of 10 μg L⁻¹ for ciprofloxacin and marbofloxacin, 13 μg L⁻¹ for enrofloxacin and danofloxacin, 22 μg L⁻¹ for norfloxacin, 29 μg L⁻¹ for sarafloxacin, and 30 μg L⁻¹ for ofloxacin. For the screening detection of quinolones, ciprofloxacin was used as model with decision limit (CCα) and detection capability (CCβ) of 103 and 106 μg L⁻¹, respectively. High cross-reactivity (> 100%) was obtained to all assayed quinolones while negligible cross-reactivity (< 0.1%) to other antibiotics (β-lactams, aminoglycosides, macrolides, tetracyclines, and sulfamides) was observed. The validation provided evidence that the method is suitable to be applied in routine analysis for the detection of quinolones in bovine milk.

喹诺酮是兽医学中广泛使用的处方抗生素家族。过量使用可能导致动物源食品中喹诺酮残留。因此，已经开发并验证了微孔板中的磁免疫荧光测定法可筛选牛乳中的喹诺酮。该测定基于间接竞争方法，其中牛奶样品中的喹诺酮与固定在磁珠上的喹诺酮竞争抗喹诺酮抗体。然后，加入抗IgG抗体标记的过氧化物酶及其各自的底物，荧光信号与喹诺酮浓度间接相关。根据参考方法获得的结果，在脱脂，全脂和原奶样品中，喹诺酮类药物的回收率为82％至102％。环丙沙星和马波沙星为^-1，恩诺沙星和达诺沙星为13μgL ^-1，诺氟沙星为22μgL ^-1，沙拉沙星为29μgL ^-1，氧氟沙星为30μgL ^-1。对于喹诺酮类药物的筛选检测，以环丙沙星为模型，其决策极限（CCα）和检测能力（CCβ）分别为103和106μgL ^-1。与所有测定的喹诺酮类药物均具有较高的交叉反应性（> 100％），而与其他抗生素（β-内酰胺类，氨基糖苷类，大环内酯类，四环素类和磺酰胺类）的交叉反应性则可忽略不计（<0.1％）。验证提供了该方法适用于常规分析以检测牛乳中喹诺酮的证据。