Methylmercury in water samples at the pg/L level by online preconcentration liquid chromatography cold vapor-atomic fluorescence spectrometry

Ultra-traces of methylmercury at the sub-ppt level can be magnified in the foodweb and is of concern. In environmental monitoring a routine robust analytical method is needed to determine methylmercury in water. The development of an analytical method for ultra-trace speciation analysis of methylmer...

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Bibliographic Details
Published in:Spectrochimica acta. Part B: Atomic spectroscopy 2015-03, Vol.105, p.103-108
Main Authors: Brombach, Christoph-Cornelius, Chen, Bin, Corns, Warren T., Feldmann, Jörg, Krupp, Eva M.
Format: Article
Language:English
Subjects:
Atomic fluorescence spectrometry
Fluorescence
Liquid chromatography
Mathematical analysis
Mercury (metal)
Methylmercury speciation
Preconcentration
Sea water
Sorption
Spectrometry
Spectroscopy
Ultra-traces
Water
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Summary:Ultra-traces of methylmercury at the sub-ppt level can be magnified in the foodweb and is of concern. In environmental monitoring a routine robust analytical method is needed to determine methylmercury in water. The development of an analytical method for ultra-trace speciation analysis of methylmercury (MeHg) in water samples is described. The approach is based on HPLC-CV-AFS with on-line preconcentration of water samples up to 200mL, resulting in a detection limit of 40pg/L (ppq) for MeHg, expressed as Hg. The unit consists of an optimized preconcentration column filled with a sulfur-based sorption material, on which mercury species are preconcentrated and subsequently eluted, separated and detected via HPLC-CV-AFS (high performance liquid chromatography–cold vapor atomic fluorescence spectrometry). During the method development a type of adsorbate material, the pH dependence, the sample load rate and the carry-over were investigated using breakthrough experiments. The method shows broad pH stability in the range of pH0 to 7, without the need for buffer addition and shows limited matrix effects so that MeHg is quantitatively recovered from sewage, river and seawater directly in the acidified samples without sample preparation. •We demonstrate that a novel mixture of thiourea-thiolsilica shows an excellent trapping of MeHg between a broad pH range 1–6.•We develop the method so that it can potentially be automated for inorganic and methyl-mercury.•The method is matrix independent with highly accurate results for MeHg in hair CRM extracts and spiked water samples•The limit of detection is around 40pg/L when just 200mL sample is used, without any intensive preparation
ISSN:0584-8547
1873-3565
DOI:10.1016/j.sab.2014.09.014