Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/5/2010
Publication Date: 1/12/2011
Citation: Chen, G., Du, Y. 2011. Screening of Danofloxacin residue in bovine tissue by terbium-sensitized luminescence on C18 sorbent strips. Journal of Agricultural and Food Chemistry. 59:1058-1062. Interpretive Summary: Danofloxacin (DANO) is an effective antibiotic drug approved by the Food and Drug Administration (FDA) to use in cattle industry, and the residue level was set at 200 parts per billion (ppb) in beef muscle. To protect consumer health, its residue level in beef must be monitoring. Conventional quantitative methods rely upon sophisticated sample preparation and chromatography to extract and separate the analyte resulting in low productivity and high assay cost. A new method was developed that achieved effective extraction, cleanup, and enrichment using small (25x10 mm) sorbent strips cut from commercial thin-layer chromatography plates, followed by time-resolved luminescence (TRL) directly measured on the sorbent surface. This method was successfully applied to DANO screening in beef at 200 ppb. With rapid protocol and low cost, this screening method can be used in regulatory practice to target DANO and other quinolone drug residues in foods.
Technical Abstract: Danofloxacin (DANO) residue in bovine muscle was screened at 200 ng/g by terbium-sensitized luminescence (TSL) directly measured on 10x6 mm C18 sorbent strips. The analyte was first adsorbed on sorbent surface by immersion in defatted homogenates. After reagent application and desiccation, TSL was directly measured on sorbent surfaces at 273 nm excitation and 546 nm emission wavelengths. The luminescence intensity was linearly dependent on DANO concentration in the 0-1000 ng/g range (R2=0.9983). A threshold was established from TSL signals at 200 ng/g fortification as average minus three times standard deviation. Among 30 blind samples randomly fortified at 0-1000 ng/g, 29 were screened correctly, only 1 negative sample was presumed positive. This simple screening protocol has the potential to significantly reduce sample numbers, hence improve sample throughput and save assay costs.