Ionic liquid-based dispersive liquid-liquid microextraction for the separation and preconcentration of lead in water samples prior to FAAS determination without chelating agent

摘要

In the present study, an environment-friendly sample preparation method termed ionic liquid-based dispersive liquid-liquid microextraction combined with flame atomic absorption spec-trometry has been developed for the determination of Pb(Ⅱ) ion in water samples prior to flame atomic absorption spectrometry determination. In this method, ionic liquid was used as an extraction solvent instead of the organic solvent used in the conventional dispersive liquid-liquid microextraction (DLLME) assay, and there is no need for a chelating agent. Several variables that may affect extraction efficiencies, including pH, the volume of ionic liquid, the type and volume of disperser solvent, salt addition, and the time for centrifugation and extraction were studied and optimised. Under the optimised conditions, the calibration curve exhibited linearity over the range of 20.0-1000.0 μg L~(-1). The enrichment factor and the limit of detection based on 3S_b/m were 35.0 and 5.9 μg L~(-1), respectively. Seven replicate determination of a solution containing of 100.0 μg L~(-1) Pb(Ⅱ) ions gave a relative standard deviation of ±2.1%. Finally, the feasibility of the proposed method for Pb(Ⅱ) determination was assessed by the analysis of certified reference material and various water samples and the satisfactory results were obtained.