Speciation of mercury in water and biological samples by eco-friendly ultrasound-assisted deep eutectic solvent based on liquid phase microextraction with electrothermal atomic absorption spectrometry.

A simple, fast, sensitive and eco-friendly ultrasound-assisted deep eutectic solvent liquid phase microextraction (UA-DES-LPME) was developed for preconcentration and speciation of Hg2+ and CH3Hg+ combined with ETAAS. Choline-phenol based DES (1:3, molar ratio) was used as an extractant for the determination of species of mercury, Hg2+ formed hydrophobic complexes with dithizone and complexes were then extracted using DES. For CH3Hg+ determination, CH3Hg+ can be extracted directly into DES phase because of its hydrophobic property. Under optimized conditions, the detection limits of Hg2+ and CH3Hg+ were 0.073 and 0.091 ng mL-1, respectively. %RSD (n = 7) were less than 4.1% and the enrichment factor (10 mL sample volume) were 34 and 18.3 for Hg2+ and CH3Hg+, respectively. The accuracy of the developed method was verified by analysis of SRM-1566b oyster tissue. The proposed method was applied to the speciation of mercury in several water and fresh water fish samples.