In-situ derivatization and ternary supramolecular deep eutectic solvent-based dispersive liquid-liquid microextraction coupled to HPLC-FLD for the determination of sulfonamide residues in waters

A ternary supramolecular deep eutectic solvent (SUPRATDES) consisting of hydroxypropyl-β-cyclodextrin (HP-β-CD), thymol and formic acid was newly synthesized in this work. Based on in-situ derivatization (ISD) and the SUPRATDES, a new vortex-assisted dispersive liquid-liquid microextraction (ISD-SUPRATDES-VA-DLLME) method was first developed and coupled to HPLC-fluorescence detection for the sensitive quantitation of sulfonamides (SAs) residues in water. Upon in-situ derivatizing SAs in sample with fluorescamine and employing the as-synthesized SUPRATDES as the extractant in VA-DLLME procedure, an improvement in comprehensive extraction efficiencies up to 26% was achieved compared with the corresponding DES without β-CD. The important parameters in ISD-SUPRATDES-VA-DLLME were evaluated by one-factor-at-a-time (OFAT) experiments and further optimized by central composite design (CCD). Based on the optimized parameter conditions, the method exhibited an excellent linear range from 0.012 to 300 μg L −1 ( R 2  > 0.9994) and low limits of detection (LOD) ranged from 0.0035 to 0.0076 μg L −1 . Both the intra-day and inter-day precision ( n  = 6) were ≤9%, and the obtained enrichment factors (EFs) were varied between 210 and 530. Spiked recoveries of 80.2–114.8% were achieved and insignificant matrix effect (ME of 0.90–1.05) was found for real samples with different matrices. The mechanism of ISD and synergistic extraction of β-CD was investigated with the aid of HPLC-MS, density functional theory (DFT) calculation and molecular docking analysis. This proposed method demonstrated low LODs, high EFs, short extraction time and eco-friendliness, thus offering a novel alternative for the enrichment and detection of multiple SAs in aqueous environment samples.