Determination of ciprofloxacin and enrofloxacin in edible animal tissues by terbium-sensitized luminescence.

A terbium-sensitized luminescence method is described for the determination of the sum of residues of enrofloxacin and its major metabolite ciprofloxacin in edible animal tissues. Several parameters affecting both detection and extraction were studied. Analytes were extracted from spiked samples of chicken and trout tissues with pH 7.4 buffer-dichloromethane. The organic extract was evaporated and the residue dissolved in aqueous nitric acid and defatted with hexane. Determination was carried out directly in the aqueous phase (in a micellar medium). The calibration curves were linear up to 75 micrograms l-1. The detection limit was 3.5 micrograms kg-1 (for a 5 g sample) and the repeatability was 7.0% (n = 7). The sensitivity was similar for both quinolones and therefore calibration can be carried out with either ciprofloxacin or enrofloxacin. In any case, the differences were < 10%.