Ionic Liquid-based Hollow Fiber Liquid–Liquid–Liquid Microextraction Combined with Capillary Electrophoresis for the Determination of Sulfonamides in Aquaculture Waters

Ionic liquid-based hollow-fiber liquid–liquid–liquid microextraction (IL-HF-LLLME) coupled to capillary electrophoresis (CE) has been developed for the determination of six sulfonamides (SAs) in aquaculture waters. A series of extraction parameters was optimized to enhance the extraction efficiency, which included type and pore size of hollow fiber, type and composition of extraction solvent, pH value of donor phase, the concentration of acceptor phase and the mass ratio of donor phase to acceptor phase along with extraction temperature and time. Under optimal conditions, the IL-HF-LLLME-CE method provided a wide liner range for six SAs from 2 to 1,000 μg L−1 (r2 ≥ 0.9995), the limits of the detection from 0.25 to 0.48 and the enrichment factors from 122 to 230, respectively. Relative standard deviations for intra- and interday precision were 1.4–5.3% and 1.8–7.5% (n = 5), respectively. The proposed method was successfully applied for the determination of trace-level SAs in seven real-world aquaculture water samples with good recoveries (80.4–100.7%). Also, sulfamerazine and sulfamethoxazole were detected at the level of 0.52–1.60 μg L−1 in two water samples. Due to its good sensitivity, simple operation, short analysis time and eco-friendliness, the developed method has a great application potential in analysis of trace SA residues in aquaculture waters.