Synchronized separation, concentration and determination of trace chloramphenicol, thiamphenicol and florfenicol in food by using polyoxyethylene cetyl ether-salt aqueous two-phase system coupled with high-performance liquid chromatography

As a novel and green pretreatment technique to trace samples, polyoxyethylene cetyl ether (POELE20)–(NH 4 ) 2 SO 4 aqueous two-phase extraction system was coupled with high-performance liquid chromatography to analyse synchronously chloramphenicol (CAP), thiamphenicol (TAP) and florfenicol (FF) in chicken and pork samples. It was found that the extraction efficiency ( E %) and enrichment factor ( F ) of the three antibiotics were influenced by the types of salts, the concentration of salt, the concentration of POELE20, system temperature and pH. The final optimal condition was as following: the phase-forming salt is (NH 4 ) 2 SO 4 , the concentration of (NH 4 ) 2 SO 4 is 0.141 g mL −1 , the concentration of POELE20 is 0.03 g mL −1 , the temperature is 298.15 K, and the system pH is 4.5. This POELE20–(NH 4 ) 2 SO 4 ATPS was applied to separate and enrich three antibiotics in real sample under the optimal conditions, and it was found that the recovery was 97.20–102.00 % with a RSD of 0.61–4.85 %. The limit of detection for CAP, TAP and FF were 0.10, 0.50 and 0.50 μg kg −1 , and the limit of quantitation for CAP, TAP and FF was 0.15, 1.50 and 1.50 μg kg −1 . Seven times the experiments were used to verify the repeatability and veracity of this method, and the RSD for the intra-day and inter-day were 1.13–3.22 and 1.74–4.72 %.