Combination of dispersive liquid-liquid microextraction based on ionic liquid and pre-column fluorescence derivatization-high performance liquid chromatography for determination of eight sulfonamides in water samples

Dispersive liquid-liquid microextraction based on ionic liquid coupled with high performance liquid chromatography (HPLC) and pre-column fluorescent derivatization method (IL-DLLME-HPLC-FL) was developed for the determination of eight sulfonamides (SAs). The influence of IL-DLLME parameters on extraction efficiency and the stability of derivatives of the eight SAs were investigated. The optimized experimental conditions were as follows: 40 µL [C6MIM][PF6] as extraction solvent, 0.1 mL acetone as dispersion solvents; water sample with 0% NaCl (pH 4) was extracted by dispersive liquid-liquid microextraction without ultrasonic-assistance and then derivatized for 6 h. Under the optimized experimental conditions, the results indicated that the eight sulfanilamides showed good linearities when their mass concentrations were in 0. 2-10 µg/L and 10-500 µg/L, and the linear correlation coefficients were no less than 0. 9989. The detection limits ranged from 0. 08 µg/L to 0. 5 µg/L (S/N=3). The proposed method was applied to the analysis of four water samples from different sources (tap water, lake water, Pearl River water and pond water). The relative recoveries of the SAs spiked in water samples were 87. 2% - 101. 4% with the relative standard deviations of 3. 7% - 6. 2% at three different concentration levels of 5, 50 and 200 µg/L. It is a convenient, environmental friendly method for the routine analysis of SAs in water samples.