New method for determination of isotope dilution in foodstuffs
NMKL method No. 202, "Methylmercury: determination by isotope dilution GC-ICPMS in foodstuffs", describes the quantitative determination of mono-methylmercury (MMHg) (10-5000 µg/kg dry weight) in mainly marine biota samples. The principle of the method is that the sample is spiked with an appropriate amount of Hg isotope-enriched MMHg and extracted. After derivatisation the sample is analysed using GC-ICPMS. The GC separates the different mercury species before MMHg is atomised and ionised in the high temperature of the ICP. The ions are extracted from the plasma, and in a mass spectrometer the ions are separated by their mass/charge ratio.