Atomic fluorescence spectrometric detection of methylmercury in seawater at sub ng L−1 level by UV-induced atomization of gaseous methylethylmercury after NaBEt4 derivatization with purge and trap preconcentration and gas chromatography separation

Abstract

A sensitive method for methylmercury (MeHg) analysis in seawater by UV-induced atomization of methylethylmercury (MeHgEt) based on NaBEt4 derivatization with purge and trap preconcentration and gas chromatography- atomic fluorescence spectrometry (GC-AFS) detection was developed. The UV atomizer was demonstrated successfully to atomize MeHgEt to Hg0 with low temperature (<45 °C) and low consumption (11 W). The effects of UV lamp power, the quartz tube length, the GC carrier gas flow rate and the NaBEt4 concentration on MeHg determination were optimized. The relative standard deviations obtained from 0.25 ng L−1 MeHg was 3.5%. The detection limits was calculated as 0.0002 ng L−1 for MeHg, which not only reduced two orders of magnitude compared to the solid-phase extraction and cation or anion exchange column preconcentration methods, but also was comparable or even better than the thermal decomposition and dielectric barrier discharge (DBD) atomization methods after NaBEt4 or NaBPr4 derivatization with purge and trap preconcentration. In addition, compared with KBH4 as reductant without preconcentration, the detection limit of this method was nearly reduced six orders of magnitude for MeHg. The accuracy of the proposed method was also validated by analyzing a certified reference sample (GBW08675) with a satisfactory result and successfully applied to the determination of MeHg in sub ng L−1 level in different seawater samples.