Comparison of hydrophilic and hydrophobic deep eutectic solvents for pretreatment determination of sulfonamides from aqueous environments

Abstract

Seven hydrophilic and hydrophobic deep eutectic solvents (DESs) were prepared. The physical properties, water solubility, viscosity, density and freezing point of DESs were determined. The characterization of DESs was performed by Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy. The extraction efficiencies accomplished by two distinct approaches, namely, dispersive liquid–liquid microextraction (DLLM) with hydrophobic DESs and the aqueous two-phase system (ATPSs) with hydrophilic DESs were compared. ATPSs based on hydrophilic DES were used to extract sulfonamides, revealing good extraction efficiency. The optimum extraction conditions were the concentration of K₂HPO₄ being 0.2 g mL⁻¹ and the volume of DES being 200 μL. Under these conditions, the satisfactory recoveries of the proposed method investigated ranged from 87.7 to 95.6% with the relative standard deviation (RSD) of 0.9–3.1% (n = 3). The linear range was 0.10–50.0 μg mL⁻¹ for the four sulfonamides. The limits of detection were in the range from 0.003 to 0.006 μg mL⁻¹ and the limits of quantification were in the range from 0.010 to 0.020 μg mL⁻¹. The results indicated that the proposed method was successfully applied for monitoring sulfonamides in water samples.