METHYL MERCURY DETERMINATION IN ENVIRONMENTAL AND BIOLOGICAL REFERENCE AND OTHER MATERIALS BY QUALITY-CONTROL WITH CERTIFIED REFERENCE MATERIALS (CRMS)

Two concentration methods - HCl extraction and extraction followed by water vapour distillation - prior to anion exchange separation and cold-vapour atomic absorption spectrometry were used for the quantification of methyl mercury in a number of reference materials of biological and environmental origin with reference or certified total mercury contents. The applied methods were validated by the analysis of three marine reference materials, certified for methyl mercury. The results obtained in the materials with methyl mercury contents ranging from less than 1 mug/kg to a few hundred mug/kg showed good agreement between both methods for biological materials, whereas extraction/anion exchange resulted in somewhat too high values for a number of environmental materials. These findings, however, require further confirmation by additional methods and by other laboratories.