Determination of antibiotics enrofloxacin, ciprofloxacin and norfloxacin in poultry or feather meal by microwave assisted extraction (MAE) followed by RPLC-DAD or HILIC-MS / MS liquid chromatography

"The aim of this work was to optimize processes to determine the antibiotics enrofloxacin, ciprofloxacin and norfloxacin in poultry and feather meal, used in feeds composed of animal remains that are not commercialized to the public. The meals were processed using microwave assisted extraction (MAE) and solid phase extraction (SPE). For the detection and quantification of antibiotics, were used: reverse phase liquid chromatography coupled to a diode detector (RPLC-DAD) and liquid chromatography by hydrophilic interaction coupled to a diode detector (HILIC-DAD) or tandem mass spectrometry (HILIC -MS / MS). Using the RPLC-DAD it was found that the optimized conditions for MAE consisted of using methanol/ formic acid (95: 5 v / v) at 30 ° C for 15 min. Using HILIC-DAD, it was verified that optimized SPE conditions consisted of the use of Oasis HLB cartridges (60 mg, 3 mL), with final elution of the sample in methanol. In addition, this method allowed to optimize the eluents used, being acetonitrile and 5 mM ammonium acetate at pH 3.5 chosen as the most suitable. The use of the optimized HILIC-MS / MS methods showed that the method was specific for the determination of enrofloxacin in poultry meal, with precision from 11 to 18% and accuracy from 103 to 105% for samples doped before MAE with a concentration higher than 37 μg / kg, this value being considered as the limit of quantification (LOQ). The method was considered specific for the detection and monitoring of enrofloxacin, with the LOQ value being below the legal limit for this antibiotic in products of animal origin for human consumption. Analysis of bird meal samples confirmed the presence of enrofloxacin at non-quantifiable concentrations. "