Mercury speciation in hair by headspace injection-gas chromatography-atomic fluorescence spectrometry (methylmercury) and combustion-atomic absorption spectrometry (total Hg).

The speciation of Hg in human hair was carried out with combustion-atomic absorption spectrometry for total Hg (THg) and headspace-gas chromatography-atomic fluorescence spectrometry (HS-GC-AFS) for methylmercury (MMHg). The determination of total Hg in hair was carried out with the AMA analyzer (Advanced Mercury Analyser 254). Accuracy and reproducibility were assessed on a Certified Reference hair sample (IAEA-086 CRM), yielding, respectively, a recovery of 97.5% and a RSD of 3.2%. Analyses of 10 blank measurements resulted in a detection limit of 1.5 ng g(-1) of THg for a 20mg sample of human hair. MMHg concentrations in hair were assessed with HS-GC-AFS in a single analysis step. Either acid or alkaline extraction can be applied because they yielded very similar results on a IAEA-086 CRM: we observed a recovery of 103% and a RSD of 7% with acid extraction and a recovery of 110% and a RSD of 9% with alkaline extraction. Optimization of the headspace vial, injection and GC parameters is described. The detection limit of the MMHg determination in human hair, which amounts to 0.04 ng g(-1) for a 20mg sample, is far below the concentrations observed in natural samples. The number of samples that can be analyzed per hour, respectively, amounts to 8 for THg and 4 for MMHg. Finally, Hg speciation in natural human hair samples was carried out by combining both AMA and HS-GC-AFS analysis methods. THg levels were at the µg g(-1), level, with an average MMHg fraction of about 70%.

Arsenic speciation in the River Zenne, Belgium.

Arsenic species have been assessed in the Zenne River, a sewage contaminated tributary of the Scheldt estuary, in winter 2003. The highest total dissolved As concentrations were found in the middle part of the river with values up to 3.6 microg L(-1). Particulate As concentrations increase towards the mouth of the River with highest levels of 2 microg L(-1). A very good correlation between the % of dissolved As and % of dissolved Fe was observed. They both linearly decrease with the amount of dissolved oxygen. In the middle part of the Zenne River where the oxygen levels were lowest, even below 1 mg L(-1), As(III) was the dominant species. In the other parts (upstream and downstream) of the river, As(V) was dominant. A linear relation between the measured redox values and those calculated via the As(III)/As(V) couple exists, but the range of measured Eh values is much larger than the calculated ones. No methylated dissolved As species were found during our survey.