Combining GC–MS/MS with a LLE-SPE sample pretreatment step to simultaneously analyse enrofloxacin and ofloxacin residues in chicken tissues and pork

A widely applicable original gas chromatography–tandem mass spectrometry (GC–MS/MS) method was explored to qualitatively and quantitatively measure enrofloxacin and ofloxacin residues in chicken tissues and pork. The experimental samples were processed based on liquid–liquid extraction (LLE) and solid-phase extraction (SPE). Trimethylsilyl diazomethane (TMSD) was chosen to react derivatively with enrofloxacin and ofloxacin. In total, 78.25% ∼ 90.56% enrofloxacin and 78.43% ∼ 91.86% ofloxacin was recovered from the blank fortified samples. The limits of detection (LODs) were 0.7–1.0 μg/kg and 0.1–0.2 μg/kg, respectively. The limits of quantitation (LOQs) were 1.6–1.9 μg/kg and 0.3–0.4 μg/kg, respectively. It was verified that various experimental data met the requirements of the FAO & WHO (2014) for the detection of veterinary drug residues. Real samples obtained from local markets were analysed using the established method, and no residues of enrofloxacin or ofloxacin were detected in the samples.