Preconcentration and separation of trace roxithromycin by [Bmim]BF4 - Na2CO3 Aqueous two-phase flotation system

Combining solvent sublation with ionic liquid aqueous two-phase extraction (ILATPE), ionic liquid aqueous two-phase flotation (ILATPF) was proposed for preconcentration and separation of antibiotics in environment. The new technique was applied to preconcentrate and separate trace roxithromycin (ROX) in the environment using 1-butyl-3-methylimidazolium-tetrafluoroborate ([Bmim]BF₄) ionic liquid as a green sublation solvent prior to molecular fluorescence spectrometry determination. Several factors affecting the extraction efficiency containing pH, conditions for phase separation, sublation time and gas flow rate were investigated and discussed in detail. The determination of ROX from practical samples offered satisfying extraction efficiency under the optimal conditions. The limit of detection (LOD) was 0.04 μg mL^-1 and the relative standard deviation of 0.4 μg mL^-1 ROX for 10 parallel determinations was lower than 0.77%. The concentration multiple of this method was 22.25 which was much larger than that of ILATPE.