Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/11/2012
Publication Date: 1/9/2013
Publication URL: http://handle.nal.usda.gov/10113/57407
Citation: Chen, G., Li, Q. 2013. Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup. Journal of Agricultural and Food Chemistry. 61:98-102. Interpretive Summary: A screening method was developed to target residues of two fluoroquinolones (FQs), enrofloxacin (ENRO) and ciprofloxacin (CIPRO), in swine liver at 500 parts per billion tolerance set by the Food and Drug Administration. After extraction, cleanup was carried out by dispersive liquid-liquid microextraction (DLLME) using a minute amount of chloroform. Detection followed by terbium-sensitized luminescence (TSL). A common screen threshold was derived from ciprofloxacin that has the lower TSL response between the two targets, and applied to both FQs. Thirty seven samples randomly spiked with ENRO or CIPRO up to 200% of tolerance were screened without false negatives, and only 3 negatives were presumed positive. This method minimized usage of chlorinated solvent, lowered assay cost, and improved sample throughput in regulatory monitoring.
Technical Abstract: A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally detected by terbium-sensitized luminescence (TSL) using a time-resolved luminescence photometer. CIPRO’s TSL response was found slightly lower than ENRO’s, so a common threshold was derived from CIPRO and applied to both FQs. Among 37 samples randomly spiked with CIPRO or ENRO up to 1 ug/g, all 22 positive samples were screened correctly without false negatives, but 3 among 15 negatives were presumed positive. This method minimized use of chlorinated solvents, and significantly improved sample throughput.