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.

Determination of organic and inorganic mercury species in water and sediment samples by HPLC on-line coupled with ICP-MS.

This paper describes a preconcentration method for Hg(2+) and MeHg(+) in water samples using sodium diethyldithiocarbamate immobilized in polyurethane foam (PU-NaDDC) and an extraction method for several mercury species in sediment samples, including MeHg(+), EtHg(+) and PhHg(+), which is simple, rapid, and uses a single organic solvent. Separation and measurement were done by high-performance liquid chromatography on-line with inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Initially, the test of recovery was applied using procedures compatible with HPLC. Under the optimum extraction conditions, recoveries of 96.7, 96.3 and 97.3% were obtained for MeHg(+), EtHg(+), and PhHg(+), respectively, from n=4 spiked sediment samples. This study also demonstrates that the combination of solid-phase extraction on PU-NaDDC with HPLC separation and ICP-MS detection is an effective preconcentration procedure for simultaneous measurement of Hg(2+) and MeHg(+) at ultra-trace levels in water samples. The application of the proposed procedure to the determination of mercury species in drinking water sample was investigated. The proposed method clearly gave satisfactory average recoveries between 93.7 and 101.5%.