Stability study on a Westoo-based methodology to determine organomercury compounds in polluted soil samples

This paper concerns with the evaluation of a speciation methodology for organomercury compounds in soil samples. The methodology used is based on the Westoo method, which includes an acid leaching of the soil followed by an organic solvent extraction and a re-extraction with a selective aqueous reagent (cysteine). The separation and quantification of organomercury compounds is achieved by capillary electrophoresis technique, using an ultraviolet-visible detection system (HPCE-UV). The main steps in the speciation process are discussed, from the point of view of possible degradation processes. Frozen, de-frozen and non-frozen soil samples have been analyzed, characterizing the influence of light and temperature. Equally, the effect of light and temperature, as well as the chemical form of cysteine, have been analyzed on aqueous extracts. Organomercury degradation has been observed in the aqueous phase and related results are discussed. (C) 2003 Elsevier Science B.V. All rights reserved.