Synchronized separation, concentration and determination of trace sulfadiazine and sulfamethazine in food and environment by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled to high-performance liquid chromatography

Polyoxyethylene lauryl ether (POELE10)-Na 2 C 4 H 4 O 6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027   g   mL −1 , the concentration of Na 2 C 4 H 4 O 6 is 0.180   g   mL −1 and the temperature is 35   °C. This POELE10-Na 2 C 4 H 4 O 6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20–99.52% with RSD of 0.35–3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52–3.64   pg   mL −1 , and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41–12.15   pg   mL −1 .