Separation/enrichment of trace tetracycline antibiotics in water by [Bmim]BF4–(NH4)2SO4 aqueous two-phase solvent sublation

A new preconcentration/separation method of [Bmim]BF4–(NH4)2SO4 aqueous two-phase solvent sublation was established and used to analyze tetracycline antibiotics, including tetracycline (TC) and oxytetracycline (OTC). The optimal conditions were investigated and discussed. The real water samples containing TC/OTC were analyzed, and the results were satisfying. The detection limits (LOD) of TC and OTC are 41.7 μg L− 1 and 52.1 μg L− 1, respectively. The relative standard deviation of 0.04 mg mL− 1 TC/OTC for 10 parallel determinations is less than 2.5%. Molar absorptivities (ε) of TC and OTC are 1.65 × 104 L mol− 1 cm−1 and 1.3 × 104 L mol−1 cm−1, respectively. [Bmim]BF4–(NH4)2SO4 aqueous two-phase solvent sublation is shown to be promising for the separation and enrichment of trace TC/OTC as well as other substances in the environment.