| 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 |