A rapid dispersive liquid-liquid microextraction based on hydrophobic deep eutectic solvent for selective and sensitive preconcentration of thorium in water and rock samples: A multivariate study

Thorium [Th(IV)] and its compounds are highly toxic and cause severe damage to bone and kidney through long term exposures. Conventional methods of Th(IV) detection are complicated and costly. In this study, we developed a new dispersive liquid-liquid microextraction (DLLME) based on hydrophobic deep eutectic solvent (HDES) for preconcentration of Th(IV) in water and rock samples prior to UV-Vis. spectrophotometric detection. The microextraction procedure was carried out by applying thorin as a chelating agent, cethyltriniethyl ammonium bromide (CTAB) as an ion pairing agent and a DES consisted of 1-hexyl-3-methylimidazolium and salicylic acid components as an extraction solvent. Central composite design (CCD) was applied to obtain the best condition of the microextraction procedure. The developed method is a green, facile, fast, selective and sensitive that could detect Th(IV) in the concentration range of 10-600 ng mL(-1) with a limit of detection (LOD) and preconcentration factor of 2.1 ng mL(-1) and 59, respectively. The relative standard deviation of five replicate measurements of Th(IV) at 100 ng mL(-1) was 1.7%. Finally, the proposed method was successfully applied to the analysis of Th(IV) in water and rock samples, and desirable results were obtained. (C) 2019 Published by Elsevier B.V.