Assessment of dispersive liquid-liquid microextraction for the simultaneous extraction, preconcentration, and derivatization of Hg2+ and CH3Hg+ for further determination by GC-MS.

This work reports the development of a dispersive liquid-liquid microextraction method for the simultaneous extraction, preconcentration, and derivatization of Hg(2+) and CH3Hg(+) species from water samples for further determination by GC-MS. Some parameters of the proposed method, such as volume and type of disperser and extraction solvent, and Na[B(C6H5)4] concentration were investigated using response surface methodology. Suitable recoveries were obtained using 80 μL C2 Cl4 (as extraction solvent), 1000 μL ethanol (as disperser solvent), and 300 μL 2.1 mmol/L Na[B(C6H5)4] (as derivatizing agent). Accuracy was evaluated in terms of recovery and ranged from 87 to 99% with RSD values <7%. In addition, a certified reference material of water (NIST 1641d) was analyzed and agreed with the certified value about 107% (for Hg(2+)), with RSD values <8.5%. LODs were 0.3 and 0.2 μg/L, with enrichment factors of 112 and 115 for Hg(2+) and CH3Hg(+), respectively. The optimized method was applied for the determination of Hg(2+) and CH3Hg(+) in tap, well, and lake water samples.