Antibodies to the quinolones and fluoroquinolones for the development of generic and specific immunoassays for detection of these residues in animal products

Several quinolone and fluoroquinolone haptens have been used to raise polyclonal antibodies exhibiting both specific and generic properties for these classes of antimicrobial compounds. The antisera have been assessed in rapid enzyme immunoassays (ELISAs) designed to exploit the specificities obtained. A direct generic ELISA for both the quinolones and fluoroquinolones has been developed that uses the cross-reactivity of an antibody raised against norfloxacin (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid) linked to ovalbumin via a secondary amine group on the piperazinyl moiety to detect nine different drugs in these classes. Specific ELISAs to ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinoline carboxylic acid), enrofloxacin (1-cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid), flumequin (9-fluoro-6,7-dihydro-5-methyl-1-oxo-1H,5H-benzo(ij)quinolizine-2-carboxylic acid) and nalidixic acid (1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid) have also been developed with a high degree of specificity to the individual compounds. The assays measure drug residues in bovine milk and ovine kidney with an interassay relative standard deviation (s r ) of 10.5% or less and intra-assay s r of 11.2% or less. Sensitivity is less than 4 μg kg -1 for both the generic and specific assays for all but one of the compounds tested. (Pipemidic acid (8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acid) is detectable at 6 μg kg -1 in kidney.)