Application of ionic liquid-based air-assisted dispersive liquid–liquid microextraction combined with high-performance liquid chromatography for the determination of six tetracyclines in honey

A novel ionic liquid-based air-assisted dispersive liquid–liquid microextraction combined with high-performance liquid chromatographic method was developed for the simultaneous analysis of oxytetracycline, tetracycline, demeclocycline, metacycline, chlortetracycline and doxycycline in honey. Tetracyclines in samples were extracted with ethyl acetate-[Bmim]PF6 under acidic condition with the assistance of air. The analytes were separated on a C18 column thermostated at 20 °C under gradient condition with a mobile phase consisted of methanol and oxalic acid. Parameters for the extraction (pH, dilution buffer, ionic strength, volumes of ionic liquid and ethyl acetate, assistance techniques and extraction time) were evaluated. The developed method showed good linearities over the range of 10.0–500 μg/L (R2 > 0.999). The enrichment factors were 16.6–41.2. The detection limits and quantification limits were 0.434–0.919 μg/kg and 1.45–3.06 μg/kg, respectively. The recoveries were 89.5–116%. The intra-day and inter-day RSDs were 0.644–6.44% and 2.35–15.9%, respectively. The developed method is sensitive, accurate, rapid, convenient, and is applicable for the determination of six tetracyclines in honey.