Extraction of some antibiotics from propolis samples using homogenous liquid–liquid extraction coupled with deep eutectic solvent–based hollow fibre protected preconcentration

Combination of counter current salting-out homogenous liquid–liquid extraction and deep eutectic solvent–based hollow fibre protected preconcentration method has been developed for the extraction of some antibiotics from propolis samples prior to their determination by ion mobility spectrometry. In this method, an appropriate amount of the powdered propolis is mixed with iso-propanol and deionised water to obtain a homogenous solution. Then, this solution is passed through a glass tube filled with sodium chloride. By this action, the fine droplets of iso-propanol are released and the analytes are extracted into them. The separated iso-propanol is taken and slowly entered into a hollow fibre. By doing so, the analytes are trapped in the pores of hollow fibre and the organic solvent is evaporated after a few minutes. After that, a few microlitres of a water-miscible deep eutectic solvent (prepared from N,N–dimethyl ammonium chloride and propionic acid) is added to elute the analytes from the pores of hollow fibre. Method validation studies indicated that the introduced method has low limits of detection (0.27–0.41 ng g–1) and quantification (0.91–1.37 ng g–1), high enrichment factors (562 –603) and extraction recoveries (84–90%), acceptable repeatability (relative standard deviation ≤ 9.2%) under the optimum conditions.Abbreviations: CCSHLLE: Counter current salting-–out homogenous liquid–liquid extraction; DES: Deep eutectic solvent; EF: Enrichment factor; ER: Extraction recovery; HBA: Hydrogen bond acceptor; HBD: Hydrogen bond donor; HF–LPME: Hollow fiber–liquid-phase microextraction; HPLC: High-performance liquid chromatography; IMS: Ion mobility spectrometry; LOD: Limit of detection; LOQ: Limit of quantification; LR: Linear range; RSD: Relative standard deviation.