ARS | Publication request: Screening of fluoroquinolone residues in caprine milk using a 5-kg luminescence photometer

Submitted to: Journal of Food Analytical Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2011
Publication Date: December 20, 2011
Citation: Chen, G. 2011. Screening of fluoroquinolone residues in caprine milk using a 5-kg luminescence photometer. Journal of Food Analytical Methods. 5:1114–1120.

Interpretive Summary: A terbium-sensitized luminescence (TSL) method was developed to screen presence of residues of four fluoroquinolones (FQ) registered in goat milk in the European Union (EU): enrofloxacin, ciprofloxacin, flumequine, and danofloxacin. After extraction and cleanup, TSL was measured using a portable fluorometer. Flumequine was designated to set the screening criterion; other FQ drugs can also be effectively screened because of their higher signals at their maximum residue limits. The potential of this work is to reduce a large sample pool to a small fraction, and subject only those presumptive positives to confirmation. Excellent sensitivity of our portable instrument enabled screening at rigorous EU regulation for FQ drugs at 30-100 parts per billion in milk. Satisfactory results were obtained on 48 blind samples. The method and instrumentation are both field deployable to facilitate field testing on dairy farms, and hence to promote timely decision making and food safety.

Technical Abstract: A terbium-sensitized luminescence (TSL) method was developed to screen presence of residues of four fluoroquinolones (FQ) registered in caprine milk in the European Union: enrofloxacin, ciprofloxacin, flumequine, and danofloxacin. After extraction in McIlvaine buffer and SPE cleanup, TSL was measured at excitations = 300 nm and emmision = 546 nm using a portable fluorometer. A screening threshold was established based on flumequine’s TSL signal at its maximum residue limit, the lowest among four FQs. Among 48 blind samples randomly fortified with one FQ up to three times of its MRL were 12 false positives and no false negative. This field deployable protocol has the potential to significantly reduce sample numbers for confirmation, hence improves sample throughput and saves assay costs.