Deep eutectic solvent-based emulsification liquid-liquid microextraction coupled with gas chromatography for the determination of thiophenols in water samples

A simple, fast, cheap, and effective method named deep eutectic solvent-based emulsification liquid-liquid microextraction (DES-ELLME) was employed to extract thiophenols from water samples. DES was characterized by Fourier transform-infrared (FT-IR) spectroscopy, CHN elemental analysis, and proton and carbon nuclear magnetic resonance spectroscopies ( H-1-NMR and C-13-NMR). 50 mu L DES was added to the aqueous sample solution and a uniform solution was formed immediately. After injection of 50 mu L acetone into this solution, turbidity was observed. Then, the phase separation (DES rich phase/aqueous phase) was performed by centrifugation. DES rich phase was subjected to gas chromatography with a flame ionization detector (GC-FID). Significant factors including the volume of acetone and DES, ultrasonication time, and pH were combined using a desirability function (DF) and optimized through a Box-Behnken design. Calibration graphs were linear in the concentration range of 0.02-100 mg L-1 under optimum experimental conditions; the coefficients of correlation were more than 0.999. The limits of detection and quantification were in the ranges of 10-15 mu g L-1 and 33-50 mu g L-1, respectively. This method was used to determine target analytes in spiked water samples; the relative mean recoveries were 96 to 104%.