Dispersive liquid-liquid microextraction based on deep eutectic solvent doped with hydroxyethyl-β-cyclodextrin for the determination of sulfonamides in environmental waters

A novel method was pioneered for the enrichment of six sulfonamides (SAs) in environmental waters, i.e., vortex-assisted dispersive liquid–liquid microextraction based on hydroxyethyl-β-cyclodextrin doped deep eutectic solvent (VA-DLLME-HCDDES). A hydrophobic deep eutectic solvent (HDES) was synthesized and used as an extractant based on two reaction precursors (benzyltriethylammonium chloride and thymol), and the doping of hydroxyethyl-β-cyclodextrin (HE-β-CD). The addition of HE-β-CD to the HDES greatly enhanced the enrichment factor for SAs by 21.6%. For the first time, the HE-β-CD doped HDES was demonstrated to be a supramolecular ternary DES (SUPRATDES). A multivariant methodology of Plackett-Burman design followed by central composite design was employed to screen and optimize several influencing factors in the VA-DLLME-HCDDES procedures. Under optimized conditions, the VA-DLLME-HCDDES/HPLC-PDA method showed good linear range of 1.1–500 μg L−1 (r2 > 0.9996) with the limits of detection of 0.3–1.1 μg L−1. After verification of its reliability with a certified reference standard (81267a), the newly developed method was successfully applied for the trace-level detection of SAs in environmental waters with relative recoveries of 84–112%. Overall, the prominent advantages of the proposed method are free of dispersant, easy preparation of HCDDES, environmental benignity and high extraction efficiency. Thus, the newly developed method provides a good alternative to conventional approaches for detection of SAs.