Luminescent determination of quinolones in milk samples by liquid chromatography/post-column derivatization with terbium oxide nanoparticles

The dynamic ranges of the calibration graphs and limits of detection are, respectively: 65-900 ng mL−1 and 35 ng mL−1 for marbofloxacin, 7.2-900 ng mL−1 and 2.5 ng mL−1 for ciprofloxacin, 6-900 ng mL−1 and 2 ng mL−1 for danofloxacin, 50-900 ng mL−1 and 20 ng mL−1 for enrofloxacin, 35-900 ng mL−1 and 12 ng mL−1 for sarafloxacin, 5-900 ng mL−1 and 2 ng mL−1 for oxolinic acid, and 7-900 ng mL−1 and 2.5 ng mL−1 for flumequine. The precision, established at two concentration levels of each analyte and expressed as the percentage of the relative standard deviation is in the range of 1.9-8.1% using standards, and of 3.4-10.7% in the presence of milk samples. The method has been satisfactorily applied to the analysis of skimmed, semi-skimmed and whole milk samples, with recoveries ranging from 89.0 to 106.5%.