Mercury speciation in biological samples

An extraction method is proposed in order to evaluate mercury speciesin biological samples (e.g. fish, mushrooms). Sulphur-containing ligands have been considered and thiourea was chosen for the optimised extraction procedure according to the best recovery obtained (65.9%, 75.8%, 47.1% and 98.2% for CH3Hg+, C2H5Hg+, C6H5Hg+ and Hg2+ respectively)and the chromatographic performance. Thiourea solutions added to biological samples enabled extraction of organomercury species; the influence of reaction time and recovery yields were evaluated. The proposed procedure, coupled with an on-line preconcentration step, allows to reduce contamination problems and to obtain detection limits at ng/g levels. The method has been evaluate with reference materials (BCR).