The antibody specificity was determined by measuring cross-reactivity (CR) with other structural analogs. The result shows that the IC50 of RHA™ anti-Ofloxacin monoclonal antibody, clone OFX was 1.17 ng/mL. The CR with pefloxacin was 9.345%, the CR with lomefloxacin, norfloxacin, pazufloxacin, enrofloxacin, ciprofloxacin, enoxacin, tusofloxacin, and nadifloxacin were all