Separation, enrichment and determination of ciprofloxacin using thermoseparating polymer aqueous two-phase system combined with high performance liquid chromatography in milk, egg, and shrimp samples.

Aqueous two-phase systems (ATPS) are potential industrial technology in separation and enrichment areas. However, the main problem is that ATPS could not be recycled, which results in a high cost and pollution of the environment. In this work, a new ATPS which formed by thermoseparating polymer EOPO with phosphate was developed for the separation and enrichment of ciprofloxacin (CIP). In the first procedure, the single factors have been discussed. The results showed that when the amounts of EOPO (80%, w/w) and K2HPO4 (55%, w/w) were 3.0 mL, 7.0 mL, respectively, pH=11, the extraction efficiency of CIP could reach 97.7%. In the second extraction, with the temperature induced, the extraction efficiency of CIP showed 85.6%. Additionally, the phase components were successfully recycled and reused for more than two times. The new method was successfully applied to the determination of CIP in real samples with detection limits of 6.8 ng g(-1).