Uncertainty contributions to species specific isotope dilution analysis. Part 1. Characterisation and stability of 199 Hg and 13 C isotopically enriched methylmercury by 1 H NMR

199 Hg-enriched methylmercurychloride has been synthesised, purified, and characterised by 1H nuclear magnetic resonance spectroscopy (NMR) for use in species specific isotope dilution analysis (IDA). The stability of methylmercury during the analytical procedure was investigated using 199Hg and 13C isotopically labelled methylmercury analogues and 1H NMR spectroscopy. The halide order of preference for methylmercury was found to be I > Br > Cl. No evidence was found for the decomposition, or formation of methylmercury during equilibration with soil (NIST 2710) or dogfish muscle (DORM-2), or during the chromatographic separations.