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)–(NH4)2SO4 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 (NH4)2SO4, the concentration of (NH4)2SO4 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–(NH4)2SO4 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 %.