Quantitation and validation of fluoroquinolones in eggs using liquid chromatography/tandem mass spectrometry.

Fluoroquinolone antibiotics are labeled for very limited veterinary use for treatment of some animals and pets, but they are not authorized for food animals in Canada, including egg-producing birds. Because they are approved for other animals, however, fluoroquinolones may appear in eggs through off-labeling or accidental use. This method is capable of quantitating and confirming the presence of 4 fluoroquinolones, ciprofloxacin, danofloxacin, enrofloxacin, and sarafloxacin, over the concentration range 1 to 60 microg/kg (ppb) using 2 internal standards, norfloxacin or lomefloxacin. The compounds are extracted with acidic acetonitrile, isolated using Oasis HLB solid-phase extraction, and quantitated by liquid chromatography/tandem mass spectrometry at 2 transitions. The limits of detection (microg/kg) were evaluated from between-day experiments as: ciprofloxacin, 0.22; danofloxacin (m/z 314), 0.32; enrofloxacin, 0.22; and sarafloxacin, 0.31. The values for the decision limit, CCalpha were 0.33, 0.36, 0.30, and 0.45 microg/kg, respectively.