The partitioning of acetylspiramycin was carried out in an aqueous two-phase system (ATPS) formed by a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoraborate, [Bmim]BF4) and NaH2PO4. This ATPS is a simple, non-toxic and effective sample pretreatment technique, which was developed for the simultaneous separation, enrichment and rapid analysis of acetylspiramycin coupled with molecular fluorescence spectrophotometry. Analysis of the liquid-liquid equilibrium of [Bmim]BF4-salt ATPS demonstrated that the salting-out ability of different salts may be related to the Gibbs energy of hydration of the ions. The effects of types of salts, concentration of NaH2PO4, and temperature were analysed. Under optimum conditions, the average extraction efficiency and partition coefficient were 90.14% and 91.1, respectively. Thermodynamic functions provide some information about the molecular mechanism involved in acetylspiramycin transfer to the top phase, suggesting an important acetylspiramycin-[Bmim]BF4 interaction. The method yielded a linear range in the concentration from 1.0 to 10.0 µg mL−1 of acetylspiramycin, and the limit of detection was 0.02 µg mL−1. This method could be successfully applied for the analysis of acetylspiramycin in lake water, river water and groundwater. The proposed extraction technique appears to be suitable as a first step for the separation of macrolide antibiotics from real aqueous environments.
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