Development of a UPLC-FLD method for quantitative analysis of three tetracyclines and two fluoroquinolones in chicken muscle

• Simultaneous determination of tetracycline, oxytetracycline, doxycycline, enrofloxacin and ciprofloxacin residues in chicken muscles by UPLC-FLD. • The fluorescence detector output signals were processed by dual-channel detection. • The sample pretreatment process was optimized. A sensitive, rapid and efficient ultra-performance liquid chromatography-fluorescence detection (UPLC-FLD) method was established for detecting tetracycline (TC), oxytetracycline (OTC), doxycycline (DOX), enrofloxacin (ENR) and ciprofloxacin (CIP) residues in chicken muscle. Moreover, the fluorescence detector output signals were processed by dual-channel detection. The samples were extracted with a mixture of acetonitrile and 0.1 M citric acid containing 100 mM magnesium chloride (1:1, V/V, adjusted the pH to 5.0 with ammonia) using liquid-liquid extraction (LLE) and purified by Oasis PRiME hydrophilic-lipophilic balance (HLB) solid-phase extraction (SPE) cartridges (60 mg/3 mL). The target compounds were separated on an ACQUITY UPLC BEH C 18 (100 mm × 2.1 mm, 1.7 μm) chromatographic column using a mobile phase composed of acetonitrile and 0.1 M malonic acid solution containing 50 mM magnesium chloride hexahydrate, and the pH was adjusted to 5.5 by adding ammonia. The limits of detection (LODs) and limits of quantification (LOQs) of the five target compounds in chicken muscle were 0.1–13.1 μg/kg and 0.4–39.4 μg/kg, respectively. The recoveries of the five target compounds in chicken muscles were above 87.33 % when the spiked concentrations were at the LOQ, 0.5 maximum residue limit (MRL), 1.0 MRL and 2.0 MRL. The intraday relative standard deviations (RSDs) were less than 4.91 %, and the interday RSDs were less than 5.13 %. Ultimately, this novel detection method was successfully applied to the quantitative analysis of TC, OTC, DOX, ENR and CIP in 20 commercial chicken samples from local supermarkets.