Simultaneous Detection of Ofloxacin and Lomefloxacin in Milk byVisualized Microplate Array.

A sensitive, simple, inexpensive, simultaneous analytical method for ofloxacin and lomefloxacin in milk by immunoassay without the need of time-consuming or complex pre-treatment steps was reported. A 96-well microplate was used as solid support, on which ofloxacin antigen and lomefloxacin antigen were immobilized, respectively. After immobilization, a mixture of relevant antibodies and standard solutions containing the analytes or samples were added to the array reaction area, then added silver nanoparticles (AgNPs) labeled secondary antibody. Silver enhancement technique was applied to amplify the detection signals, which produced black image on array spots visible with naked eyes. The signals were detected with a microarray scanner; therefore the analyte residues could detect quantitatively. The Limits of Detection (LOD) (3SD) were estimated to be 0.24 ng/mL (ofloxacin) and 0.35 ng/mL (lomefloxacin).